To make this possible now, you need to set movementclass for the buildings. and also you need to add mass for them, like 99999 so they dont move when something explodes near them.
But this aint so good, because:
- Transportable buildings doesnt leave ghost.
- It gives sometimes movement error messages.
- Units dont know how to circulate buildings, so they gets sometimes stuck to transportable buildings.
It would be much easier if we had that variable.
Would it be much work to add such variable in the unit handler engine?
And if you have better idea to make buildings possible to be transported, please tell it!

BTW, why its not possible to move labs?