put it on your little finger and make a small hook shape before you put it in and then it should nearly touch the cheek, then you can straighten the finger and rub it on the gums, it worked for me, you have to be a bit quick though!!
lol, thanks posters, thats come in handy for me too, my 20 week old daughter has cut her 1st tooth today. You need the nimble fingers of a concert pianist!
yes, once some teeth are through and they are still teething, getting the gel in becomes like sticking your hand in an aligator! (though not as sharp!)
Also try Ashton and Parsons herbal teething powder - I've heard its supposed to be fantastic - better than the gel! - think you can get it from most chemists.
another thing to try is to put a layer on baby's (cleaned) teething ring. my 6month old won't open her mouth if she sees my finger coming, plus she bites - even with the 'hook' method! She loves her teething ring though :)