I'd poke around the Runescape forums or "google" to see if anyone has done this. What we know is that the code folk write in JAVA could have dependencies on the platform. That is, it may not run everywhere. Today I find most folk unwilling to accomodate other OSes or users that don't have any interest in programming, that is, dive in and fix the errors.

In short, find a linux runescape discussion with google.