the in game consol is non functional so there is no way but if there was you would have to type /map dm?mohdm6 or /map ojb/obj_team1 to switch between the mapes also to switch gameplay you would type /g_gametype 1-4 1-4 is the different types of gameplay but since there is no list i can only assume that 1 is dm 2 is team dm 3 is round and 4 is objective... but non of these commands work
unless you are running a dedicated server then the functional commands are
status
restart
kill
kick
map
set fraglimit
all the other commands are nonfunctional or at least all the other q3 dedicated server commands i have tried were non functional
hope that helps