All, Looks like I finally figured it out! Here's what I did to get everything to work:
1) PS3: Delete all game-data from mw3
2) PS3: I installed the fix-bundle of 1.19-1.20-1.21 (100MB) [thanks Levyn]
> used Call Of Duty MW3-BLUS30838.Patch.v1.19.v1.20.and.v1.21.Install.and. Crack.CFW.3.41-3.55-PS3JB
3) PC: then I downloaded the original patches 1.22 and 1.23 for MY version: bles01431 (you do yours ofc)
> used the following packages listed below [thanks kalaner] http://b0.ww.np.dl.playstation.net/t...2-V0100-PE.pkg http://b0.ww.np.dl.playstation.net/t...3-V0100-PE.pkg
4) PC: Extracted both, copied 1.23 over 1.22 (overwrite all files). [used ps3 tools > pkgview]
5) PC: Extract the new nodrm 1.23 fix and copy &replace to the folder from above (EXCEPT PARAM.SFO) [only 3 files]
6) PC: Edit the PARAM.SFO (which would be the one from 1.23-original) to set FW-ver to 3.40 ->save/replace [i did 3.40 and worked fine for me]
7) Then copy all files over to your ps3 to dev_hdd0/game/BLES01431 (you do your ID ofc)
8) PS3: Mount game & play (for online FckPSN is needed ofc)
I have tested this multiple times last night and this morning, both exiting and starting the game back up in XMB as well as rebooting. It is completely stable, plus no prompt to update to 4.0! All spec ops and multiplayer matches work perfectly. Hope this info helps.
P.S. If this has helped you, then take some time to help me out. I really want the new DLC maps primarily for specs ops survival to play both offline and online. As of right now, it seems the only way to get the latest maps is to download it from the PSN store? Also, still trying to figure out how to even download free content as well. Still receiving the same 80029780 error code. Please let me know when you guys get a chance.
P.S.S Special thanks to Blade86 and to everyone else who've helped along the way. Take carez!