[CentOS] Hard-set network via ifup scripts...

Anyone know off the top of their head the "right" way to hard set a
link automatically to 100Mbps Full Duplex, etc using the ifup or ifcfg
files?

Don't see options in the scripts that might cover this, but maybe
there's a more elegant way to do it than to do something in rc.local or
hack up the ifup files myself...

Ray