I'm replying to myself in case it can be usefull to somebody else.
I found the problem. Looks like Tomcat could not find javac.exe. When i added %JAVA_HOME%\bin to the PATH it started to work.
In the web.xml in the SAR, you can configure Jasper. Here, you can try to set the "fork" parameter to "false".
Just tried it myself. This was preventing me from using JBoss+TomCat for the longest time. And I am glad to say that it works well. Thanks for the info.
Save problem using Jetty. Same solution. Thanks for the follow-up post.