When I replaced my valve cover gaskets I was also replacing my entire intake manifold and so it was easier to do.
I have read of a few people just loosening up their intake manifold but not removing it and were able to replace the valve cover gaskets. But, after doing mine I just don't see how that would have been possible.
Replacing the gaskets is easy, it's just very time consuming due to all of the stuff you have to unplug, disconnect, move out of the way and etc. And I cleaned up the gasket mating surfaces really well so that added extra time.
I don't remember there being anything tricky about it. No caveats or gotcha's or anything like that. I didn't use any RTV sealant or anything and have been leak free ever since. Well, actually, one thing I can think of is the connector body of the CHT connector may have become very brittle and may fall apart in your hands. My connector did but it was before I replaced my valve cover gaskets. Ok, maybe there's more;
IF you do remove your intake manifold, I found it easier to do by removing the driver side wheel and fender liner. It makes getting at those intake manifold bolts much easier.
EDIT: I think the Ford part number for the bolt and grommet is 6K562A (1S7Z-6K562-AA) but they are expensive. I'll continue to see if I can find that post with the alternate grommets.
EDIT-2: Well I found
the post I was thinking of but unfortunately it does not have an acceptable substitute.