This was way harder than it needed to be because of all the outdated information out there.
Starting with ARK4 and DC-ARK (aka ARK DC?), I kept getting an error on the PSP itself that pointed me to "Team C+D mspformat PC Tool" that apparently only runs on 32-bit Windows XP or some crap. You don't need that. And the ARK-4 readme points you to MagicMemoryCreator which requires Python and command prompts that I don't understand and you don't either. That's all unnecessary too. There was also Resizer Portable which was an "improved" method, but who knows when in the timeline that was, and it didn't work anyway.
It took a video from one of the legends of the PSP scene to point me to the right direction. You just need a PSP utility called PSP Tool.
Here's exactly what I did, even if some parts were redundant:
- Run PSP Tool, format memory card. PSP restarts.
- Copy over PSP Tool again and run it, and choose to create Magic Memory Stick. When it's done (takes several minutes), press Home to exit.
- Copy over firmware 6.61 to the root of the Magic Memory Stick (and name it 661.PBP or 661GO.PBP for PSPgo), and run DC-ARK This also takes several minutes.
When it's all done, you'll be back at the XMB. Shutdown and place that memory stick some place safe.