I'd recommend you take a shot running nsjava unless you really need nstomcat (.jsp pages? can nsjava be made to serve these, too?)
The main reason is that nstomcat talks to the DB via JDBC. This isn't a very efficient way to talk to PG, one of the key virtues of AOLserver is its management of database handles, something you really don't want to lose when working in Java in the AOLserver environment.
