Player, the projectile trick is nice, but doesn't work in this case, where you cannot specify the house (because it has yet to be build).
There is no other way to do this, so you might want to reconsider the compromis of a gather point for the villagers (it's quite logical that new-born units just walk to the town center automatically, isn't it? They have to register, etc )Well, another, lot-of-work way of doing this is to place cinematic blocks of an unused player X all over the map, like one per tile. Then, create a trigger for each and every one:
Conditions:
- units in area (center unit block, unit type house, player X, radius > 3)
- units in area (center unit block, unit type house, player X, radius < 8)Effect:
- Change unit type, source unit block, unit type villager.
After you've created one of such triggers, it only takes 10 mouseclicks (copy trigger, click name field, go to conditions, select block, click center, next condition, click center, go to effects, click source unit, go back to triggers) and a few keyboard ticks (depending on the name) per cinematic block. If you're a real pro at mouseclicking, and if you don't have RSI, this might take about 7 seconds per trigger. Considering a not-too-big 300x300 map, you'll need 90000x7=630000 seconds=10500 minutes=175 hours.
Not worth it, in my humble opinion.