Today an Eboot Fix for Call of Duty Modern Warfare 3 patch 1.21. It was orginally signed with for OFW 4.00 but with this Param.sfo and a few patches it will be up and running to work with the latest version of FckPSN. Check out the download and the tutorial below.
1) Download official update 1.21
2) Then replace files in dev_hdd0/games/blus30838 with the fix pack
3) Play Online Via FckPSN