[Uim] Documentation, or just help?

[Sunnan]

Hi, I'm using swedish-postfix method in LEIM on emacs most of the time. 
It's a simple method based on composition.

I'd like to have something similar available in gtk and mozilla.

What do I have to read and do to get this working? Should I use UIM or 
something else? I'm lost in the world of input methods!

I'm familiar with the Scheme programming language.

Thanks,
Sunnan