The only thing I do with my right hand (mouse) that's necessary for combat is turn the camera. I use a razer nostromo now, but this was true before I got it and was using a keyboard, too. Movement is WASD, Tab for targeting, skills on keybinds (1-6, QERTY, FGH, ZXCVBN, plus alt and shift mods of all those). If I were to move some things around (combine cooldowns, use hotbar swap macros, etc.), I'd be able to find room for camera control keys.
What it comes down to is how many keys other than movement and camera you can comfortably hit during combat, and which modifiers you can comfortably use for those keybinds.
What I'd suggest is getting your main rotational abilities (DK, TwS, Snap, Boot, TS, Demo, ToD) onto keys that are the are easiest for you to hit. Then prioritize the off-GCD stuff (Tackle, Howling Fist, Steal Peak, IR, B4B, Featherfoot, Mantra, Second Wind). If you're comfortable with modifiers, stick things together with some kind of theme. For example, all your flank moves unmodified, all your rear moves alt, all your AOE on shift; all your offensive buffs unmodified, defensive on alt, off-GCD attacks (tackle, howl, peak) on shift. Or openers unmodified, middle moves on alt, end moves on shift. Just something you can remember and use.
If you're not comfortable with modifiers, my next suggestion would be rotating hotbars/skills via macro, again with some kind of theme per bar. Similar moves in the same spots on each bar, with one button to cycle from one bar to the next.