I created a ejbtimerDS-ds.xml which uses MySQL. The GeneralPurposeDatabasePersistencePlugin in $JBOSS_HOME/server/$PROFILE/deploy/ejb2-timers-service.xml uses the GeneralPurposeDatabasePersistencePlugin for MySQL.
The exception below occurs on startup when JBoss starts.

With debug=true for the CachedConnectionManager in $JBOSS_HOME/server/$PROFILE//deploy/jca-jboss-beans.xml

17:17:06,041 INFO [ConnectionFactoryBindingService] Bound ConnectionManager 'jboss.jca:service=DataSourceBinding,name=ejbtimerDS' to JNDI name 'java:ejbtimerDS'
17:17:06,521 WARN [WrappedConnection] Closing a result set you left open! Please close it yourself.
java.lang.Throwable: STACKTRACE
at org.jboss.resource.adapter.jdbc.WrappedStatement.registerResultSet(WrappedStatement.java:909)
at org.jboss.resource.adapter.jdbc.WrappedPreparedStatement.executeQuery(WrappedPreparedStatement.java:343)
at org.jboss.ejb.txtimer.GeneralPurposeDatabasePersistencePlugin.isNextDateColumnPresent(GeneralPurposeDatabasePersistencePlugin.java:595)
at org.jboss.ejb.txtimer.GeneralPurposeDatabasePersistencePlugin.createTableIfNotExists(GeneralPurposeDatabasePersistencePlugin.java:178)
at org.jboss.ejb.txtimer.DatabasePersistencePolicy.startService(DatabasePersistencePolicy.java:104)
at org.jboss.system.ServiceMBeanSupport.jbossInternalStart(ServiceMBeanSupport.java:376)
at org.jboss.system.ServiceMBeanSupport.jbossInternalLifecycle(ServiceMBeanSupport.java:322)
at sun.reflect.GeneratedMethodAccessor109.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.jboss.mx.interceptor.ReflectedDispatcher.invoke(ReflectedDispatcher.java:157)
at org.jboss.mx.server.Invocation.dispatch(Invocation.java:96)
at org.jboss.mx.server.Invocation.invoke(Invocation.java:88)
at org.jboss.mx.server.AbstractMBeanInvoker.invoke(AbstractMBeanInvoker.java:264)
at org.jboss.mx.server.MBeanServerImpl.invoke(MBeanServerImpl.java:668)
at org.jboss.system.microcontainer.ServiceProxy.invoke(ServiceProxy.java:189)
at $Proxy38.start(Unknown Source)
at org.jboss.system.microcontainer.StartStopLifecycleAction.installAction(StartStopLifecycleAction.java:42)
at org.jboss.system.microcontainer.StartStopLifecycleAction.installAction(StartStopLifecycleAction.java:37)
at org.jboss.dependency.plugins.action.SimpleControllerContextAction.simpleInstallAction(SimpleControllerContextAction.java:62)
at org.jboss.dependency.plugins.action.AccessControllerContextAction.install(AccessControllerContextAction.java:71)
at org.jboss.dependency.plugins.AbstractControllerContextActions.install(AbstractControllerContextActions.java:51)
at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
at org.jboss.system.microcontainer.ServiceControllerContext.install(ServiceControllerContext.java:297)
at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1652)
at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:938)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:988)
at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:826)
at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:556)
at org.jboss.system.ServiceController.doChange(ServiceController.java:688)
at org.jboss.system.ServiceController.start(ServiceController.java:460)
at org.jboss.system.deployers.ServiceDeployer.start(ServiceDeployer.java:163)
at org.jboss.system.deployers.ServiceDeployer.deploy(ServiceDeployer.java:99)
at org.jboss.system.deployers.ServiceDeployer.deploy(ServiceDeployer.java:46)
at org.jboss.deployers.spi.deployer.helpers.AbstractSimpleRealDeployer.internalDeploy(AbstractSimpleRealDeployer.java:62)
at org.jboss.deployers.spi.deployer.helpers.AbstractRealDeployer.deploy(AbstractRealDeployer.java:55)
at org.jboss.deployers.plugins.deployers.DeployerWrapper.deploy(DeployerWrapper.java:179)
at org.jboss.deployers.plugins.deployers.DeployersImpl.doDeploy(DeployersImpl.java:1454)
at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1172)
at org.jboss.deployers.plugins.deployers.DeployersImpl.doInstallParentFirst(DeployersImpl.java:1193)
at org.jboss.deployers.plugins.deployers.DeployersImpl.install(DeployersImpl.java:1113)
at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1652)
at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:938)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:988)
at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:826)
at org.jboss.dependency.plugins.AbstractController.change(AbstractController.java:556)
at org.jboss.deployers.plugins.deployers.DeployersImpl.process(DeployersImpl.java:789)
at org.jboss.deployers.plugins.main.MainDeployerImpl.process(MainDeployerImpl.java:699)
at org.jboss.system.server.profileservice.repository.MainDeployerAdapter.process(MainDeployerAdapter.java:117)
at org.jboss.system.server.profileservice.repository.ProfileDeployAction.install(ProfileDeployAction.java:70)
at org.jboss.system.server.profileservice.repository.AbstractProfileAction.install(AbstractProfileAction.java:53)
at org.jboss.system.server.profileservice.repository.AbstractProfileService.install(AbstractProfileService.java:403)
at org.jboss.dependency.plugins.AbstractControllerContext.install(AbstractControllerContext.java:348)
at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:1652)
at org.jboss.dependency.plugins.AbstractController.incrementState(AbstractController.java:938)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:1082)
at org.jboss.dependency.plugins.AbstractController.resolveContexts(AbstractController.java:988)
at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:778)
at org.jboss.dependency.plugins.AbstractController.install(AbstractController.java:543)
at org.jboss.system.server.profileservice.repository.AbstractProfileService.registerProfile(AbstractProfileService.java:308)
at org.jboss.system.server.profileservice.ProfileServiceBootstrap.start(ProfileServiceBootstrap.java:256)
at org.jboss.bootstrap.AbstractServerImpl.start(AbstractServerImpl.java:461)
at org.jboss.Main.boot(Main.java:221)
at org.jboss.Main$1.run(Main.java:556)
at java.lang.Thread.run(Thread.java:619)