i have a mouse with 2 left keys i use them for trowing nades, very handy. and i use scrole up and down for wapen change. 8)
im the same as snake, but i opted to get rid of the smokes and keep one of the thumbs for bashing. makes it so much easier
I use the arrow keys to run around, so I mapped the nade keys to numpad 1 and smoke to numpad 4. Scrolling down with my mousewheel is how I switch between the 2 guns... Not as effective as I would like, but there are only 2 weapons.