use the command:
q3map -game jo yourmapname.map
from radiant you can enter this in file|project settings.
The best way to do this is to probably edit an existing command and replace all references of -game ja to -game jo. this will add a new command rather than overwriting it.
Alternatively, there is a small 3rd party applet that uses a windows gui to let you set options to your hearts desire. Search on pcgamemods or jk3files for this as I have completely forgotten what it's called.
The final option it to learn how to use the command line interface - you can find help for this on
www.shaderlab.com).