who gets the fa cup europa league spot 2012 if chelsea win champions league?

Nobody. Liverpool have already qualified for the Europa League via winning the League (Carling) Cup.

And Chelsea have already qualified via League position, regardless of whether they win the Champions League. Winning the Champions League will merely certify Champions League football for Chelsea next season, it won't have any effect on anyone else (except the team who finishes 4th) getting into Europe.

So, assuming Chelsea DON'T win the Champions League, the teams finishing 1st, 2nd and 3rd enter the Champions League. The team finishing 4th enter the Champions League Play-Off Qualifying Round.

5th and 6th place enter the Europa League.

Liverpool enter the Europa League.

It doesn't matter who wins the FA Cup, in regards to European qualification as both teams in the Final have already qualified by other means.

If Chelsea DO win the Champions League then 1st and 2nd and Chelsea will enter the Champions League. 3rd place will enter the Champions League Play-Off Qualifying Round.

4th (assuming this is NOT Chelsea), 5/6th (depending on which spot Chelsea occupy) and Liverpool enter the Europa League.

If Chelsea do finish 4th and win the Champions League(highly unlikely), then the Qualification process is exactly the same as if they DON'T win the Champions League with the notable exception of 4th goes straight in and 3rd plays in the Play-Off round.

I know that seems like a lot to take in but if you read and digest it you'll make sense of it. Took me a while to understand the qualification process but I do as I have paid VERY close attention too it.