Your answer depends on whether he entered the US legally. If so, then I suggest you contact an immigration attorney. If not, there is unfortunately no relief for those who entered without inspection.
My website is www.michiganattorney.com
If he entered illegally, then he would need to qualify for 245(i) in order to be able to get the green card in the US. To qualify for 245(i), he would need to have been in the US on December 20, 2000 and have had a petition filed for him on or before April 30, 2001. If he does not meet both of these requirements, and entered the US illegally, then he cannot get the green card in the US and would have to process abroad.
However, if he has been in the US illegally for 180 days or more, he will be barred from returning to the US for three years from the date he leaves, and if he has been in the US illegally for one year or more, he will be barred for ten years.
The answer depends on whether he entered legally. If he did, then you can petition for him by filing an I-130 application, along with an application for adjustment. The adjustment application is expensive and complicated. You can find these forms along with their instructions at us is.gov.
If he entered without inspection he will qualify only if he was here on December 2000 and he filed an application before April 30, 2001.