Tried faffing around with long nose pliers, screwdrivers and such and as my eyesight decrease and fingers are getting chubby i had run out of options and patience.
Yesterday i thought i'd try a different approach.
A 7mm drill, the blunt end of a 1/4 drive - deep socket and some vaseline.
I filled the void inside the stem seal with vaseline and pushed them home with the socket and a little bit of wiggling.
Only one took more than 60 seconds, ironically the one with the new valve guide in it!

If this isn't what your doing now i believe it could be worth a try.
If you fill the void space with grease, as it compresses it opens the seal up to allow it to slide on!
AL