Yes, change the files in /tftpboot/linux/pxelinux.cfg/
In default.menu, install, install3264 and install-x64 you would want to change the append initrd=bladiblah thing. I do not know if every file needs to be adjusted, it not worth the effort to me.
I always remove the 'quiet' and 'splash' options, so I can see what is going on. On some crappy computers the boot sometimes hangs. A client with multiple network cards hangs a few minutes at a certain point, but will continue after that.
So any append lines in those pxe files look like this:
Code: Alles auswählen
append initrd=miniroot.bz2 video=vesa:ywrap,mtrr vga=791 --no-log lang=en service=https://your-opsi-server.domain.tld:4447/rpc
So to change the language to french, you would insert the 'lang=en' parameter