Oh, that reminds me.
Bushings can be tough to get out sometimes (Just the first one- second one can be easily knocked out from behind). If chiseling away at the metal edges does not work, you can drill a hole through the face of one bushing, then insert a punch to knock out the other one from behind. In fact, this is perhaps even easier than messing with the chisel in the first place...
Your 'nut & bolt' install technique will work, though the force still must be applied the the metal rings around the edges, as opposed to the metal faces. Hard to explain why without show & tell, but basically, the inner metal tubes on the bushings collide with each other before the outer rings seat on the CA. Put another way, the rubber in between gives before transmitting enough force to the outer rings.
I'm pretty sure my 'special install tool' is a 2 inch female pipe fitting with the first 1/4 or so of threads ground away. After knocking them in part way with a hammer, I put one 'tool' over each bushing, and squeeze them both home at once in a vise.
Without a vise, I could imagine getting threaded male caps for the open ends of my fittings, and drilling a hole in the center of each cap to accept the threaded rod. 2 washers, 2 nuts, some torque, and you are good to go...
Best of luck.
1986 300E 5-Speed 240k mi.