The Intuos 4 probably came with a rocker button.
I have mine set with the top of it as right-mouse click, and the side closer to the nib as middle click. Under pen options I'm using click-and-tap method rather than hover-click, as it is more precise not having to fiddle with pen buttons while finessing the pen. Most people map them the other way, but I find the top rocker easier to find reliably with my fingers, and use rightmouse a lot more than middle mouse. I don't mind fishing for the other button to zoom and scroll.
For keys (i am right handed so it may be more convenient to reverse)
Left Side: ctrl, cmd, shift, opt/alt, pan/scroll
Right Side: Display toggle, tab, escape, delete, undo
With these I can do most things without taking my hand off the tablet, and having the modifiers on the left, and action keys on the right, lets me double hand to do things like alt-tab etc.
Using this setup I can do 90% of my work without having to hit the keyboard for modifier keys or common commands, and the pen can duplicate most of the functions I would hit the mouse for.
Oh, touch strips - I have them set up for scroll and zoom. They work with modifiers too.
I may tweak this setup specifically for 3dc a bit, but it's generally good. Refinements I've been thinking of are, putting in a radial menu for the popups I use most often; eg. e-menu, color picker, brush picker, ref images panel, etc. Hope this helps.
