I am working on a 3 fold a4 brochure in indesign cs4. I found a template with all the guides and margins but it is only for one side of the paper. Since the folded parts are not of equal width, I will need to flip the spread to have the correct dimensions for the back side.
Is there a way to do this? Or is there any other way to carry all the margin and guide info to the back side?
No. You can not "flip" a page and guides in Indesign.
In CS5+ you can rotate a page 180 degrees, but that's not really what you want since rotating a page rotates everything on that page or to be placed on that page. Rotating isn't the same as flipping.
You can "flip" elements. You could easily draw a rectangle at the page edge, then draw standard lines where the guides are located, select all, copy. Create a new page, paste, flip horizontally, move into position (so the page rectangle lines up with page), then drag guides out for the new page and place them where your lines are. Then simply delete all the drawn objects.