I do know quite a bit about runescape cheating.. (I don't play anymore, so it's really not worth it to ask me much) but one thing you should do is head on over to the message board at http://www.kaitnieks.com. Probably the biggest cheating forum around for runescape; they have modified, deobfuscated* versions of the clients, and scripts. Smile
* this is sort of programming talk.. But to "obfuscate" [link] source code is just another way to say "scramble" or "make unreadable". Which was done by jagex not so long ago because of the way Java works..
Let me explain how it works quickly.
C++ - Compiled Language
Perl - Interpreted Language (for the most part, unless your using mod_perl as an extension, etc)
Java is sort of both -- It sort of "half way" compiles your source code, and is then interpreted by a virtual machine/runtime environment... So it's alot easier to "decompile" theh source code of java apps because of the fact it's not completely machine code at that point - it's merely formatted into code to be read by the interpreter. (I think, correct me if I'm wrong)
Also, I would like to add, their are sites which allow you to pay for GP/gold. (http://www.virgoods.com/buy/default.php?id=13 is a site I found)