Yes, you can. All you need to do is spoof the lower firmware version, and you'll be good to go. There are several spoofed 3.55 CFW's to version 3.72. Look in the PS3 Exploits and Hacks Section.
And then an edit to this. I don't know wtf you're trying to ask. You're wanting to do the mods for MW2 on 1.12. With all of the tutorials on how to place a MW2 patch on your jailbroken system, you're asking this, right? I'd go into detail but I'll do this instead. And to put the patch on your 3.72 PS3 system, all you need to do is do a data transfer from your 3.55 system to your 3.72 system. :y:
Here's how to install patches on a 3.55 system:
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