I'm just guessing here m8, never done ps2 patch before, but after reading the NFO here's what I'd do...
name image mrn-scpt.iso and make sure file is writable (not read only) then put the patch in with it and run it, if it doesn't work, all you've done is changed it's name... it might work though...
.oh, n make sure you have over 4Gb free