The way I do it in Eclipse is to add in a jboss server, and then alter the startup to enable debugging (see for example run.conf in the bin directory), and then just attach the debugger.
Any volunteers to write up a "debugging seam applications" article? I know I'd be interested in reading it. I've recently tried to use Netbeans and Eclipse for Seam development, but I'm just not an IDE-minded guy.
I might be able to help:
1. Edit run.bat in your jboss/bin directory.
2. Add the following line after the last "set JAVA_OPTS=" line:
set JAVA_OPTS= -Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,address=5001,server=y,suspend=n %JAVA_OPTS%
(I chose port 5001 but you can choose whatever port you want, unless it's free ;) )
3. Go to your Seam project in Eclipse, click the "Debug As" button, or just debug and select "Remote Java Application". Enter the port you chose before and click on debug.....TA DA :) (JBoss must already be running)
4. Set your breakpoints and jump for joy!