How to debug JSP running inside a portlet in WebSphere 5.0.2 with Intellij IDEA?

Question

I'm trying to remote debug JSPs using "JSR45 Compatible Server" configuration type in IDEA. My breakpoints do work in *.java files (after some dark magic tweaks, though) but breakpoints inside JSP don't. I tried settings breakpoints inside or outside scriptlets, in tag invocations, etc - none worked. WebSphere 5.0.2 runs on java 1.3.