yer can put them in with a hammer, ave done it.
not the best way thou, yer best bet is a press but as yer can't really get yer chassis in a press you'll need to make up a tool from flat bar and threaded rod
you put the threaded rod throught the bush and the spring/chassis with either a BIG washer on either end or some flat bar with a suitable hole in it. now you can use two nuts, one either end to pull the bush into place. if you happen to have a bit of pipe of suitable dia you can use that the pull them out, if they int seized too much.
as fer leccy impact drivers, you can buy a 12 volt one fer less than 40 notes in some places.
but even an impact driver wont over come bolts seized into the bush. it will just rip the rubber from the metal and spin around all day doing nowt.
If yer bolts wont come out within the first 5 mins of trying the chances are they int gonna so hack em orf and either drill or burn yer bushes out.