Nice Work.
I can finally play MGS on my pc with a gamepad.

Anyway, here is some information that you requested:
- which Linux version, which joydevice are you using?
Using Mandrake 8.2 as well as Redhat7.2. Both distros appear to work just fine.
- is the assignment of axes to up-down-left-right working properly?
Yes, perfectly... however this was not the case for lamer0's pad plugin.
- which button-layout did you choose?
I assigned each button in the config dialog box.
- what was the device file name?
/dev/input/js0
I have used two different pads with the plugin so far, 1)Gravis Gamepad Pro 2)MS Sidewinder. Both of these pads use the gameport. I have a usb pad also which I can eventually test.
Have not yet tested the plugin with pcsx. Will get back to you on that one.