For the sake of simplicity, I was trying to figure out a way to auto-fill the transfer TC username field for donations, just like PMs can:
http://forum.toribash.com/private.php?do=newpm&u=16251

Does anyone know the equivalent for the transfer TC username field, or if it's possible at all?

What do you mean?

He means being able to send someone a link to the Send TC section and a name already typed in, but unfortunately you cannot do that since that feature has not been implemented, although, you could try suggesting it in the suggestions boards.