Just made a nice crank seal driver for the right side (clutch side).  Went to Home Depot and bought a 1" electrical conduit pvc coupling and a 1" box connector bushing.  Glued the two pieces together. Then I press fit a spare crank collar (#21 in picture) into the 1" bushing bore (warmed it up to aid in assembly).  Nearly done.  I carefully filed off the molded in letters and numbers off of the face of the bushing and it's now complete.  Advantages - cheap; drives seal in square - 100%; since the OD of the flange is larger than the crankcase bore (where the seal sits), you can drive the seal in flush to the crankcase with ease.

  

Nice job! 

Better view. 
 

Pretty sure it will work well but the gap under the flange leaves it unsupported.  If it cracks at the flange upon use I'll bury the reducer so the flange is in full contact with the coupling.  Will report later. 
 

A tip I think came from Enduronut or GFrench or MDScott....  Use some windex to lube the outside of the seal and it will go in pretty easy.  Windex evaporates quick and won't permanently lube the seal like oil/grease or regular soap would...  It will go in much easier but stick in place as well as if you installed it dry.

I've also used a thin coat of blue loctite on the outside of seal.

Would that be the same principle as when using hairspray to fit handlebar grips?

The loctite is somewhat like using hairspray...  windex is more like a lube that evaporates without leaving anything slippery behind.

Thanks for the tip.  I think I'll do the Windex trick.  Might help prevent damage to the outer edges of the seal upon installation.

Windex is good for almost anything, including cuts and scrapes!
Reminds me of "My Big Greek Wedding"!