Changing margins and mirroring them for a pdf that is going to be in a small booklet format?

I have a pdf that's set on a 8.5 x 11.   I now need to print it back-to-back in a booklet that will only be 6.125" wide with the text area being 4.125", that is 1" left and right margins.  Since it's a booklet, I need to mirror the margins so that everything works for the inside (binding side) and outside edges of the 6.125" wide paper.  I can't find how to do this on Adobe.  Any suggestions would be most appreciated.