He said: "I'll be meeting the players and staff on Monday before taking charge of training.
"Then I'll have to pick a side to take on Blackpool on Saturday, because we desperately need three points."
Chairman Steve Lansdown has invited Millen to apply for the job on a permanent basis, but Millen is refusing to speculate on that yet.
He added: "The chairman rang me after meeting with Brian, he told me the news and asked if I would take temporary charge of the side.
"He also explained that applications are being taken for the post and would be happy for me to apply if I wanted to.
"It's too early to reply on that front, we'll just have to see how things go."