No-one else seems to be answering, so here goes...
You need to explain more clearly what you mean.
Is it that your different takes are played at a different tempo and you want to adjust this electronically? If this is the case I suggest that you are taking the wrong approach. You need to work on playing to a metronome, click track or drum machine to get your playing steady and consistent. If a metronome-like tempo is not appropriate, I'd suggest you should still first practise something regular against a steady beat to train your playing.
On the other hand, if you are saying that your recording gear is recording takes at different speeds, this suggests that you need to investigate the soundcard and/or its settings to sort out what is going on.
I do odd bits of recording guitar, but normally I get depressed and decide to practise for a few more days/weeks/years in the hope that eventually I'll play it right.
Thanks for your answers. My spoken/Written English is not very good (i'm french) so maybe that's why my questions look "weird". I think your first answer is the right one. In fact i played at a different tempo, and that was not the point so now 'im trying to fix it. Like you said i think it will be better to record the song with the right tempo.
But now i'll have another problem : i'm not a pathetic guitarist, but my knowledge of music theory is really low. I don't know which tempo i should use in the "metronome fonction" : For me 4/4, 4/3, etc.. it doesn't makes sense. But i don't want to bother you with basic things so i'm going to find it myself.
And lol @ Graeme.