how do I replace the functionality I need with my .Xmodmap file in Gnome 2.6?

Hi, I like where Gnome is going.

But I have one problem. My most-used application requires a compose key 
for copyright symbols and such. Up till the latest xfree86 I've been 
using .Xmodmap -- which still works with some window managers.

I was able in (Gnome 2.6's) keyboard-preferences to establish a compose 
key, but I need one more step to regain the functionality of the compose 
key with these symbols -- e.g. copyright and trademark symbols, and 
such. I couldn't figure out how to define this in keyboard-preferences 
-- the compose key with certain letters like 'c' or 'r'.

Is there a way I can regain the full functionality of my .Xmodmap file? 
I'm not stuck on sticking with that. I'd rather move ahead if that's 
going to become an anachronism.

Can you guide me on what to do? I'd like to be able to continue using Gnome.

thanks,
jamie