ID CAN be such, but IDers don't tell you this because they don't buy it normally.
Also, if IDers were to consider God an alien race, where did the aliens come from?
They don't, but they should. Believe in what you're saying, if you're going to say it at all. Instead they grasp for anything that counters evolution, without caring what that "something" would mean. ID seems far more anti-scripture than evolution, in my opinion.
"Also, if IDers were to consider God an alien race, where did the aliens come from?"
That's the same as asking where did God come from, a question that can only be danced around but never answered. 'God created Himself' is the usual dismissal. But to answer your question more directly, the aliens likely evolved by the same principles IDers deny.
I'm Catholic, and the Vatican has occasionally referenced cosmology as a plausible context for scripture. Most of their work is done in europe (astronomical research, I mean). They don't like to promote it much, probably for fear of creating fruity 'New Age' cults and spin-off religions... You say the word "alien", and next thing you have people worshiping comets and cutting their gentials off....