Ah, here's the basic steps, let me know if you need more detail on any:
1. Download source from Sourceforge (I typically use SVN to grab the latest and greatest)
2. Install the SDL packages libsdl-image1.2, libsdl-ttf2.0-0, libsdl1.2debian (might be able to use libsdl1.2debian-all instead, might need the -dev versions as well, I'm not quite sure)
3. Install FPC package fpc
4. Download JEDI-SDL from
http://jedi-sdl.pascalgamedevelopment.com/ and extract to {JEDI-SDL source}
5. Using fpc, compile the ascii version of the game somewhere to make sure it works, if you are having problems with the ascii version, the sdl version will be a nightmare (the command is fpc gearhead -dASCII)
6. Edit the file sdlutils.pas (located at {JEDI-SDL source}/sdl/pas) to make it compliant with Free PASCAL. This entails adjusting the file so all objects converted to pointers are 8 bytes instead of Turbo PASCAL's 4. I have the file done already if you need a copy.
7. Copy the sdl.inc file from {JEDI-SDL source}/sdl/pas to {JEDI-SDL source}/sdl-image/pas and {JEDI-SDL source}/sdl-ttf/pas (This is how I did it, there is probably a better way. Also, those paths are from memory, you should make sure you have yours right).
8. Finally, you can now compile. You have to include 3 JEDI-SDL folders listed above. I can get the command line I used tonight, I don't have it handy.
8a. If you want to compile GH1, you need to edit the sdlgfx.pp file to repair a call to TSDL_keyboardevent before compiling.