wwwqwerty informed us of some interesting goings-on in the 3.52 M33 firmware scene. It seems that Ketchup, PSPGen's site admin (and also a programmer), has adapted the recovery mode from 3.40 LE for use on Team M33's 3.52 M33 firmwares.

According to the information on the post, the file they've put up can also be used as a plugin without changing the recovery functions of your PSP. Here's an excerpt of the post which you guys might like:

Ketchup, with the assistance of the sources provided by the Team Wildcard which we thank here, thus adapted it plug-in to the 3.52 M33. It thus converted it plug-in and with added the functions NO-UMD which, in 3.40, was limited to a simple option ON/OFF.

To understand how to use it though, you'll want to check out the original post on PSPGen, as the file doesn't have a readme. Just use an online translation service to understand how it works.