Pickup of alien population?

[tbontob]

In a PBW game, can I pick up alien population from another player?

For example:

Assume I have a T & R treaty with a PBW player who is willing to give me 50 million of his population. Can I go to his planet and pick up the population?

If this is possible, I assume he must be the one to upload them.

If not and I am the only one who has a transport, must I gift him the transport, so he uploads the population to it and then he gifts the transport back to me