You would do a normal upload of the game and then add that file.
its the equivalent of the Windows server.exe - look in your own installed game - there is a moh_spearhead.exe and a moh_spearhead_server.exe
It has been a looooong time, so hopefully I am not off base on this, but as I recall, the trick is to do a Windows install, copy the MOH directory tree, and then add the linux executable - like sgTsTuFz said. There is some really useful info in the guide section with this thread focusing on running MOH on Linux. There are one or two added cvars for a home directory and a log directory as I recall, such as +set fs_basepath. If you search this forum for linux (be sure to show all results, not just last 30 days or whatever the default is) and you should find more information as well.