Positive Cod Points
Ok so now your at your desired rank to get positive Cod Point's you need to keep an eye on the amount you have in game.
There is no specific way of telling how many times you will need to suicide but theres a good way on figuring it out.
Join an xp lobby; kill yourself > Press start then Y now check your Cod Points (will most likely be negative, basically you need to kill yourself until that number is in the region of -2,000,000,000 (Minus 2 Billion) now the annoying part, you lose roughly 90,000,000 (90 Million) cod points a death and your points will turn positive when your points go lower than -2,147,483,647 they will then become 90,000,000 (positive points.) but at this stage you may be Rank 1 at X Prestige if this is the case you will then need to repeat this process until your are Rank 50 with Positive 90,000,000 points; it should not take anymore then 30-40 deaths.
To make the positive CoD Points stick once you've managed to get positive points then obtained host, back out; buy a few items then goto the main menu then go back onto multiplayer..
Alternately the way I did it the time in the game ran out when I was host, and my points stuck, so theirs an alternate way of doing it; just follow the same process buy a few things; go to the main menu then back onto Multiplayer.
If any of this was unclear let me know and ill address it.
It's a pain in the ass to get positive cod points. I followed the above a few years back when I did it, took my a few tries.