I found this easy way to get rid of editing the gamenumplayers thing. gets the number of players menu working correctly, the mod includes: edited uiskirmishsetup.xmb, extra ai personalities (in a separate zip inside) and a readme with instalation instructions.
it works great here but if you find aproblem let me know and ill fix it ASAP
*note some maps like river by RF_Gandalf may not work properly because it is not designed for more than 2 players