During the installation process of JBDS you can choose to Find/Add a runtime. Neither of this works on the Mac platform. I tried it with SOA-P 5.0 ER5 and also EAP 5.0 GA. On both Snow Leopard and Leopard.

When you choose Find, it simply doesn't find anything.

When you choose Add and point it to the location it shows a message: Type and Version cannont be defined for Server in selected location. You need to fill them manually.
But after I click OK, it shows "Selected Location doesn't exist" in red and I cannot click OK to add it.