[TrueLoonix]

IF that .rar contains the
msipl.bin a KD and a registry folder it might be.

That would be the step after the PSP installer was executed
beforehand you must have prepared the MS with mspformat.exe
and after you need to include the msipl.bit with msinst.exe

just follow the guides and substitute the PSP part with the extraction of the .rar to the Stick

IF you are lucky and that is no malware you should be fine

and... since the contens of that archive is copyrighted by sony it is illedal to distribute or link to it