The Croydon-born assistant manager, who played for the club as a teenager, was thrust into the Eagles hot seat for the meeting with Arsenal following Ian Holloway's departure last week.
Palace impressed despite the match ending 2-0 to the league leaders and Millen will again take the reins for Saturday's trip to West Brom.
The Hawthorns encounter may well prove to be the former Bristol City manager's last at the helm, with Palace co-chairman Steve Parish hoping to appoint a new boss by the start of next week.
Tony Pulis, Chris Coleman and Martin O'Neill are the bookmakers' favourites for a job which Millen will not be applying for.
While proud to be in temporary charge and keen to manage again, the former defender accepts he is not right man for the south London club.
"Probably the type of manager that needs to come in to look at this group from the outside would be a fresh view on what is needed, maybe some different ideas," Millen said.
"I have worked closely with the players now for a long time and I enjoy it, but I think someone from the outside coming in will give us a little bit more of a lift. It is right that I don't put myself forward for the job.
"I loved it, I really did and I have missed it, but I enjoy coaching the players as well.
"To be in charge of Crystal Palace in the Premier League was a dream come true.
"But when the game gets going, you want to win the game and I wasn't on the touchline there with a smile on my face thinking 'this is enjoyable' because we were losing after 47 minutes.
"I honestly felt when it was 1-0 that we could get something from the game, even before the sending off - that we enough chances in the game to be at least level and the players deserved that.
"I enjoyed the whole experience, but I was disappointed we didn't get something from the game because we deserved it."
While Palace do not yet have a permanent manager in place, that has not stopped the club tying key players down to new deals.
Damien Delaney penned a new contract until 2015 on Wednesday, while Millen confirmed a new contract for captain Mile Jedinak is edging ever closer.
"I think it is agreed, I don't know where we are exactly with it," he said of the Australia international, whose current deal runs out next June.
"Mile has been a great servant for the club. He is the captain, he is a leader and we want him to stay.
"We know he is happy at Crystal Palace and, while it has not been signed yet, I think it has almost been agreed.
"I am delighted for Damien. He has worked hard for it.
"He was a big part of the team last year that got promoted and he stepped up to the Premier League and has done well.
"He is back in the international fold, playing for Ireland, so he deserves it.
"He has an ankle issue at the moment that we're managing, but he is the sort of player who wants to play every game and he is the type of player you need around the place."