I forgot to post how I converted my PS1 saves for use on the PSP and I've had a couple of requests, so here's a fairly quick and dirty guide. It's a bit convoluted but the process is fairly easy, and I'll write an expanded one if anyone needs it.
You need some way to get PS1 saves to your computer in an open format (meaning copying them from the PS3 hard drive won't work for now, and as far as I can tell neither will the PS3 memory card adaptor). The way I did it was through my modded PS2, but things like a DexDrive or recent Action Replays with USB access should also be fine. If you're not going the modded PS2 route just copy the saves to your computer and skip straight to step three.
I should also note that I did this on Windows XP so I can't say whether all the little apps will work on Vista. Other than that, you just need a USB drive. Don't worry too much about space because PS1 saves are tiny (a full memory card is only 128kb).
One of the apps was quite hard to find, so I got all three of them and packaged them up
here. If you're doing this with a modded PS2 you'll also need a homebrew file browser called uLaunchELF, which you can download as an ISO and burn to a CD
here.
1. Copy saves - Boot up uLaunchELF in the PS2 and press circle to go into the file browser. Choose the MC slot with the save that you want (mc0 = slot 1; mc1 = slot 2), and in there press L1 and choose the view option that shows you the save titles. Press X on each of the ones you want to copy to mark them up, then press R1 and choose 'Copy'. Navigate back to the list of devices and go to your USB drive (mass), press R1 and choose 'Paste'. Let it copy the saves and move them over to your computer.
2. Convert raw save to .mcs - The raw saves you have at the moment are pretty much useless, so you need to convert them to a usable format. Just take the save files and drop them onto PSXRC.exe, which will pump them out in .mcs format.
3. Add saves to .mc image - Now to turn the saves into a virtual memory card image. Even if you have saves for multiple different PS1 games, you can save them into one image and convert them to the PSP, up to the standard 15 (?) blocks of an official card. Load up PSXGameEdit and go to File - New MC Image. Click the top slot and go to File - Open Single Game Save, and choose one of the saves. Repeat for each save that you want to add (obviously on a different slot each time), and when you're done go to File - Save MemCard Image, which should give you a .mc file.
4. .mc image to ePSXe image - Now you need to convert that image into ePSXe's (a PSX emulator) native memory card format, which is supported by CWCheat on the PSP. Open up PSXMemTool and load the .mc image, then just go to save it and choose ePSXe as the save format in the drop-down box. That should give you a .mcr image, which means you're finally ready to move over to the PSP.
5. CWCheat - You need to install the latest version of
CWCheat, a PSP custom firmware plugin. There are guides to installing plugins in this thread if you need help, but I found it easiest just to back up my existing plugins folder to my computer and copy over the ready-made CWCheat folder (remember to activate the pops version). Depending on the game being run on the PSP, you may also need the popsloader plugin to get the game running in the first place.
The following part is what you'll have to repeat for every game that you want to convert the save from:
When CWCheat is installed, load the game on the PSP, and when the actual game has started (after the PlayStation splash screen) hold select for three seconds to bring up the menu. Go down to 'Manage memory cards' and choose to save memory card 1 to the Memory Stick. Now quit the game and connect your PSP to your computer through USB, and go to \seplugins\cwcheat\mc\, where you should find an .mcr file. Copy its name and use it to rename the .mcr file that you made from your PS1 saves, and overwrite the one on the Memory Stick with your one.
Now go back into the game and back to the CWCheat memory card menu, where you should choose to load memory card 1 from the Memory Stick. What this essentially does is overwrite the virtual memory card that the PSP uses when emulating PS1 games with the one that you created.
How you proceed from here depends on the game. Some games (Final Fantasy VII, for example) only load the memory card when you go to load a game, in which case you can go straight into the game, find your save, load it, and then immediately save in the game so that a proper save file will be created by the PSP. Others (Metal Gear Solid does this) load the memory card in the background so that there's no delay when you go to load your save, and trying to load a save other than the one that it has already cached will cause the PSP to crash (if this happens, just hold the power switch up for ten seconds). With these games all you need to do is use CWCheat to load your memory card and then use the Home button menu on the PSP to reset the game. It'll restart with your memory card loaded from the start, allowing you to go through the same procedure: load the save and then save your game so that the PSP can create its own proper save file.
Congratulations, you've done it. You can now delete CWCheat (unless you want to keep it, of course) and put back your old plugins, as well as delete all of the files you made during the process.
Wow, that ended up being way longer than I anticipated. Hope it helps.