I gues noone is going to tell you how to do it,
1. because Speedhacks really destroy the game
( okay , tank mode is doing it also but thats something different ) .
2. E.A / B.B could fix that easy if someone says how to do it.
3. If you really want to make such kind of hacks ,
learn how to use C.E / A.M and/or OllyDbg.
Edit : Yeah , post Number 111