OFW: Official Firmware
CFW: Custom Firmware
Right, all those PSP's have the potential to run Kernel Level CFW, however without a Pandora's battery/MMS there's not a high chance of doing it.
You can do it all without spending a penny, but you have to read carefully and try not to mess up;
CFW one of your psp's;
1, Update one of your PSP's preferably the 5.02 fat too OFW 5.03
2, Load chickhen R2 using
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3, Load 5.03 Gen C using
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4, Make a Magic Memory stick, Which will install 5.00 MM3 or 5.50 gen using one of the numerous windows apps on psp-hacks.com.
5, Find a Pandora battery maker homebrew app(try psp-hacks.com), and pandorize it.
6, Use the MMS and Pandora battery on all 3 psps, yes the fat battery in the slim psp, it wont break it.
7, Now update to 5.50 gen, then all the way to gen d3.
8, Install the 5.50 prometheus addon.
9, Done. Now theres a hell of alot of work involved there, ask away if you have any trouble.
P.S. By the way I'd recommend you have a look at some of those posts over at PSP-hacks.com if you get really stuck, they've got some helpful tutorials.