im assuming you mean swap the whole axle... not just the joint.

1) pop the wheel hub nuts with a breaker bar/pipe extension while its on the ground.

2) jack it up

3) remove the upper control arm (two bolts) - should give you enough free room to wiggle the axle out

4) remove the shock so you can get the axle out

5) pop the axle out of the hub and trans

6) replace and reinstall...

unless the '91s are really different, this is just kinda generic civic/teg instruction, but its all straightforward.