Right now I am playing at cake poker and I just join all the tables at the limit I am at. This is usually 10-16 tables. They don't all come up at the same time, so I have some time to decide if I like what I am seeing. Basically it comes down to practice. I never really time out on hands and usually am on youtube or messing with itunes and checking my email... I also position myself directly between both monitors. Just keep adding tables and try and make quick decisions. It rarely gets super hectic, although it can be hard when you have 4-8 playable hands at one time. (This is were you give up some EV but try and pick it up with the 1000 hands an hour) On Full Tilt or PS I would have the hud up and have it show me the table averages and stuff. Then I could decide if I wanted to stay at a particular table.
This is probably harder to do with really aggressive opponents and/or better opponents. Cake poker is really passive so I get to control most of the action.
You do it enough and playing 4 tables becomes mind numbingly boring.