If you have a look at the Documenation for the module you load
you should be able to pass it "option=0x200" or something like
that, for my eepro100 cards this works, and sets 100Mbit/Full duplex.
This is going to be different for different cards/drivers, but if you
look for the docs. for that module in the kernel source it
should (hopefully) tell you what option to use, and what others
are avaliable, they are often interesting to read (in a very sad
Auto negotiate rarely works anyway in real world use, and
rarely sets to FULL duplex, usu. to 1/2 duplex.
It's slightly easier to use mii-tool/mii-diag (easier NOT better)
rather than using passing options to modules.