Check the pastebinned stuff. You can already do this.
For that, you need to do 6 waves, one for each lane
and that for each team (3 lanes, 2 teams = 6 waves).
There you can have n GroupSpawns, which have n delay between the last groupspawn, which have n UnitSpawn, which contains an unitID and the integer how much of them should be spawned. Additionally, you can create callback functions for example and add conditional spawning.