Midfielder Rose and central defender Caulker are highly-rated by Spurs and have been allowed to join the Robins on season-long loans in order to give them valuable first-team experience.
"It's really difficult to get these players because so many clubs are after them. It's all about building relationships and it definitely helps if you know the management at the bigger clubs," said Millen. "I've been to watch Tottenham training sessions on a number of occasions and I know Harry Redknapp, Joe Jordan and Kevin Bond. I've been down there a lot to watch practice games and got to know people that way.
"It's important to build those personal relationships so that, when you ask to take a player, the management know who you are. There is a lot of work that goes into it and we have also made good contacts at Arsenal this year.
"It's difficult for me to go sometimes because I don't have the time but if I can't go, then there are other people I can send."