Download the Toolbox from
www.filefront.com/user/mydjinnyand replace the one from FH2/binaries within the Battlefield 2 folder.
You should be able to set the number there. The FH2 menu bot toggle is messed up (I think so is the BF2 one since 1.5, not sure. I seldom play vanilla)
To fix the ratios, you want to make it 10:whatever number of players you want. So use the toolbox to get that number + 10. and then scale the ratio to dump the rest of the people on your side, fill the ranks and you're good to go
Hope this helps...
I should tell you, since Purity is no longer a developer for FH2, the Toolbox is not officially supported, although this fixed version (Original is broken) is still the best bot toggler and shouldn't screw up any other mod.