I have this: http://iforce.co.nz/i/iln4ph20.ame.jpg mounted on the bottom half of an office chair. Works good.
Get two banana boxes and sit the seat on them. Saves you damaging yourself, the chairs, or both. Try practising all of those skills on something a bit easier to start with
Orrrrrrr
Sell the seats so they don't gather dust, and buy one of these:
http://www.trademe.co.nz/Browse/SearchR ... ggested=19