You need a multiregion DVD that converts PAL to an NTSC signal (Or a Region 2 DVD and a PAL compatible display, but the 1st is the usual way to do it). Many current DVD's can be made to play UK region discs and convert PAL at least well enough to watch a decent picture. Most conversions are less than perfect, but will suffice for general viewing.
What DVD player does he have now and what kind of display?
If you are playing it on a Computer DVD player and monitor, there are many hacks that allow you to switch your current DVD drive to Region 2 and back though there are some that have a limit to the number of times you can switch.
There are many sub 100 players and quite a few sub 50 players that are easy to switch by a remote code. Toshiba's, Yamaha's are usually pretty easy. Apex, Oppo, Samsung, and a boatload of the disposable types are commonly used for multiregion play. The Oppo is probably king of the sub 200 players.
From my experience US model Sony. Pioneer, Denon, and Panasonics are more difficult to modify frequently reguiring either a hardware fix and/or a special disc.
Check over in the Regional DVD forum section and you can probably get some opinions or check what is probably the best/complete overall web site: http://www.videohelp.com/dvdhacks
Assuming the video is not copy protected, A less expensive solution is to convert the DVD to NTSC using a PC and the appopriate software. All versions of NERO Burning ROM since version 6 will do this just fine.