Steam recently changed the default privacy settings for all users. This may impact tracking. Ensure your profile has the correct settings by following the guide on our forums.
I was actually thinking of Half Byte Loader, my bad. I think there's a couple versions of eLoader (the most modern, useful one), but don't quote me on that. If I remember correctly, the versions don't have many differences either. Try looking at a compatibility list somewhere and seeing what luaplayer says.
You need a specific lua player for slim psp.
I used it in some of my older versions of Lua Player for my PSPlay application.
I'll give you a link (the eboot is really Lua Player, it just loads anything under "index.lua")
here's a link for it, just replace the necessary files (also, the eboot is going to say "PSPlay", if I come across the Lua Player that I used for it, I'll let you know) QuickJump Downloads
No problem, I remember having trouble with it when I was trying to make it compatible for Slime (I don't own a Slim model).
If I recall correctly, Axxewraith helped me out.