No, you're not missing anything. The reason we could do this in VAJ is because we had special hooks in the VAJ JVM that allowed it. But our customers complained (NO...we want to use Sun's JVM...) so we wrote WSAD to be independent of JVM -- but guess what -- Sun's JVM doesn't include this feature -- or at least didn't until we forced them to add it to JDK 1.4.
The problem is that WebSphere itself is not yet up to working on JDK 1.4 (There are a lot of issues in making an application server run on a JDK). At this point we're guessing that WebSphere 5.1 will work on the IBM JDK 1.4 ... at which point things will work the way you want them.
But in the meantime, if you're just writing straight
Java applications (without WebSphere) feel free to use Sun's JDK 1.4 with WSAD and you'll find that debugging works just the way you hope!
Kyle