Alright I got it to work.
I solved the console problem by switching the virtual console port to COM1 inside the bios setup.
Then I found out, I was modifying rd.gz from the EFI partition... which was wrong, so I modified the one from the fat partition and found out my drivers were there.
Only my libphy.ko would segfault for some reason, I've the vanilla 3.10.108 kernel sources with the browlow config, but I think I did something wrong here.
Using the ones from the tg3.7z archive posted here seems to work though.
I've just loaded the PAT file for 7.0-41222 and it's working so far.
I think a few points that would make life easier for beginners would be:
- Make sure the first partition inside the image is set "active"/"bootable" so it actually boots right after flashing it
- Add some templates/startup-scripts for loading your own kernel modules instead of having the manually hack the ramdisk
- Add some documentation on how to build your own kernel modules, e.g. which kernel sources, config and toolchain you should use for a certain version.