I was asked a couple weeks ago to do a writeup on these motor mounts. I finally got to do them today along with a ton of other stuff. So here it is.
Needed:
Floorjack and jackstands
17mm socket, rachet, extensions
Block o' wood
Grinder, hacksaw... something for cutting
x2 E28 528 motor mounts. 11 81 1 175 735 I got them from Autohausaz.com
x2 Steel spacers for the upper stud as the E28 stud is longer, 93320A321 from mcmaster.com (I cut some aluminum spacers on my lathe but these will work)
Lift the car and support it with jackstands and wheel chocks.
Remove your fan shroud hardware if you still have a fan. You don't need to remove the fan or shroud, just remove the hardware so the shroud can move when you lift the engine.
Loosen the upper motor mount nut on whichever side you're comfortable with. I went pass side. The pass side top nut can be tricky. I did it from under the car using a long handled swivle headed rachet. Once the top is undone undo the bottom nut. Place the wood block on your jack and raise the engine by the oil pan. Only raise it enough to fish the motor mount out. Watch your trans mounts... if they look stressed you may want to loosen them. Mine are new, they took it just fine.
Now for the cut. The E28 mount is offset like the M42 mount but the locating tab on the bottom is on the opposide side. Hold the two side by side an you'll see what I mean. Use a hacksaw or whatever you have to remove the tab. See image.

Now fish it back into place (you'll probably have to lift the engine more). Rotate it into position. Slowly lower the engine back onto the mount making sure the studs go into the holes. Place the steel spacer from McMaster over the top stud followed by the washer and nut. See image.

Repeat on the other side, except over here you can get to the top nut from the top of the engine compartment. Re-install fan shroud hardware.
Pat yourself on the back. You just replaced both your motor mounts for about $60 including shipping and the whole job probably took me under 45min.
Some people have said that these may cause more engine vibration in the interior. I've found this, at least in my case, to be untrue as I was replacing two VERY bad original motor mounts. My car is much smoother now.