I used to do these in place without any problems, you'll need the car quite high on axle stands or on a ramp if possible.
Using a lever bar in the bolt hole, lever the bush out, it will be tight but it'll come out with a bit of force. Then get the new one and coat the whole bush with some copper grease. You'll need to undo the beam and wedge a block of some kind between it and the body so there is a gap between the beam and the body. Put the bush in place with a block of wood under it and using a trolley jack (I used to use a gearbox jack, but if you're working on the floor a trolley jack is fine) jack the bush into place. You'll need to put quite a bit of weight in to it but it will pop in, just make sure your fingers aren't in the way, as you'll probably lose them when it goes in. Hope this helps.

If I remember rightly, we used to change one in about 15 mins this way.