weird... i did it all the way to the 10th prestige but i am wireless and used a router to do it..
**STEPS**
1. have your ps3 AND WIRELESS ROUTER both by each other.
2. go to the prestige section on cod5 and stop right before it says "theres no turning back , blahhh blahh..."
3.Timing is KEY here. now UNPLUG the power cord to your wireless router(it shouldn't disconnect you right away), wait 2-3 seconds THEN complete the prestige.
4. QUICKLY flip your ps3 system OFF using the switch in the back, IMMEDIATLY plug back in your power cord to your wireles router.
5.Flip your ps3 system back ON with the switch in the back and start up cod5.
6. If done correctly you should be ranked up ONE prestige and still be a level 65.
7.repeat steps 1-5 until you reach your desired prestige

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hope this helps! COMMENT AND REP PLZZ!!!!!