Ford Repair: rear main seal, emery cloth, jb weld

Question
I have been given a few suggestions one is to use a piece of emery cloth on all areas where the seal with touch inside and out.  The second is to pack the seal with di-electric grease.  What merit should I give these suggestions?  Also what do you mean by non-hardening sealer?

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Followup To
Question -
I am going to be replacing the rear main seal in my 1990 Bronco II are there any tips or procedures to do this?  I had to replace the seal twice in an 85 BII and I still had a leak.  I don't want to have to do it more then once.  Any help would be appreciated.
Answer -
Josh-

  No real tricks.  Just remove the old one very carefully, working from the outside only.  If you work from the indside you could nick the crankshaft's surface causing the new seal not to mount properly.  When installing the new seal just use a bit of non-hardening sealer and press it in carefully.  After that you should good to go.  Hope this helps.

Steve

Answer
Josh-

  I wouldn't use anything too abrasive on the sealing points.  It could help a bit, but you also risk a bad seal if it's overused.  As for packing it in grease, I wouldn't do that.  You run the risk of contaminating the transmission or engine oil if it decides to come off of the seal.  Non-hardening sealer is just what it sounds like...a sealer that doesn't harden after you apply it (as opposed to something like JB weld that hardens upon drying).  Permatex makes some good non-hardening sealers.  Any good automotive store should carry some.  Hope this helps.

Steve