Pre-loading siege towers with soldiers

If it's been asked before, I apologise.

I am wondering if it is possible to have siege towers pre-loaded with soldiers so that they may storm the walls of a settlement as soon as the tower makes contact.

Also, is this realistic? Were towers pre-loaded as such IRL?

A.

I don't think it's possible. The entire behavior of siege engines is hardcoded.

-Simetrical