If you are sending him a .pdf anyway, you could have the .pdf add the crop marks for you but I just openned my version 9 and there is no option for that.

When I have to make crop marks and want to make them on my own I draw a square tangent to the page corner point. Then convert outline to object, erase where it needs it and in the corner point so that doesn't show. Then I use the transform palette, I put in the numbers and tell it to duplicate. However if you flip it now. it is on the wrong side of the corner. Holding down the ctrl & the alt key, grab the left-middle edit handle and drag and it will flip it in proportion just like that.

Now you have two crop mark. Marquis select, then ctrl "G" for group. Transform and tell it how far to duplicate. Again the marks are facing the wrong way. Do the ctrl + alt trick again and you are done!

BTW, just holding down ctrl or alt individually, you can drag but it is not constained to the same size flip.

Hope this helps. Now if you upgrade to 12 which I use all the time, the .pdf export puts your crops on for you. It has the standards for professional .pdf built in. Quite handy.