Hi guys, found this on another forum and hav'nt seen it on here so thought I would let people know about it. When you have your match set up and are about to start if you rapidly press A, instead of just pressing once to start, you should see a countdown start in the top corner. This puts you on servers where the achievements are'nt glitched and you can unlock them.
Tested this with a few friends last night and we all got slippery pull and one of my friends managed to get a few others he needed. However my 360 froze a few times while trying to start a match like this and the games are supposedly really laggy (though our's were ok). Hope this helps everyone still trying to get these in system link.