Alright guys, Here's what worked for me. I did the normal LAN XP glitch until level 50, 30K or so XP from unlocking prestige. I bought a gun, a few attachments and also a new title. Then I played HC SnD/Core SnD online until I unlocked prestige. Make sure you don't leave game until it finishes. I then prestiged in the lobby and stayed in the game until rank 10 on the next prestige. I then bought the title of my new prestige and anything else I could afford. Shortly after I decided to do the LAN glitch again. So I got to 50 and went to buy things on my playercard when my PS3 froze. So i was like 'oh shit'. I rebooted my PS3 and got the corrupted error message saying I had been reset to pres. 4 lvl 10

. Just to clear things up, I began at pres. 3 lvl 20. LAN glitched till 50.
Did above steps. Then at lvl 10 pres. 4 decided to glitch again. That didn't stick but the original LAN did

. I don't know if this will be of value to any but I'ma put it out there anyway and get back to me with proggies! Hope this works for you as it did me. Enjoy.
CONCLUSION:
After some time thinking about things I believe I may have made a breakthrough. After reading what I posted above I would like to see if people agree/disagree with my conclusion here.
Ok so follow the above steps, then do LAN again once ur lvl 10 on the prestige after u XP glitched. So do it again now to lvl 50. Then prestige etc. And reboot BlOps. You should get set back to lvl 10 of that prestige. What I think is happening is:
The BlOps servers realise you XP glitched the first time but because you haven't quit the game they can't do anything about it yet. Then the server realises your doing the XP glitch again after you reach your level 10. So it thinks: 'oh shit, I better back this kid up so he/she doesn't get his next XP glitch rank to stick', so it backs you up at the current pres. level 10 your on. Then you've successfully acheived to get your prestige to stick.
Please post any feedback here or PM me

Thanks!