Everyone already uses fast weapon change...
The way that was described about tapping Q twice and such works, but there are mouses out that have an extra button between the L and R click buttons (its small though). Alot of people have that binded to weapon switch so they can keep all weapon related buttons together.
Personally, I can b-hop fine with the space bar. You learn how to do it better on surf maps and after surfing for as long as I have I can b-hop pretty easy now. I use my 3rd mouse button for flashlight
Later,
SPN-Stan