prefer shraeder here.
Admittedly it can be difficult on a full flat tyre, but just do what I do... push the tyre in at the valve stem bit so keep the valve pointing out the hole as you push the pump attachment on.
Simple, as its completely flat, tyre = floppy and easy to push
![Smiley :)](http://www.tekforums.net/Smileys/teksmileys/smiley.gif)
Presta is just an arse, with the twisty thing that I have no idea what you do with, I end up pushing the pin in with my hand and then just jamming it in the shraeder end of my foot pump.