Compiling a BlackBerry app in Eclipse with JDK 4.2.1

Question

Im trying to make an app compile in Eclipse with the BlackBerry JDK 4.2.1. As there is no plugins for this JDK version, I wrote my own definition file (.ee) based on the JDK 5.0 pointing to the 4.2.1 folders (as here). When using version 5.0 the app compiles ok, but when using the 4.2.1 version, I get this cryptic error (about rapc.exe):

I/O Error: C:\Users\Usuario\Documents\EclipseProjects\MyApp\bin (Access Denied)

Im using Windows Vista, already disabled UAC and set all the file's permission to allow access for everyone, but I still get the same error. I need to use this version because it´s the only one my device supports.

Any ideias? Thanks.