Redout, you have already (hopefully) already demonstrated your ability to plan a flight on the ground with all the normal planning facilities to hand. The diversion is to see how you can handle unplanned changes in the air - the last thing we want to see is people turning the aircraft into a planning room with CRPs and charts all over the place, accompanied by the inveitable spiral descent. You can use whatever you need, including radio navaids, but it is not a planning exercise. Probably the best way I have seen it done is just to have a straight edge marked with 5/10/15 etc nm (a ruler will do) and then once aligned with your planned track, draw it across to the nearest VOR rose - conveniently already aligned with magnetic North - and there is your track and distance. Add 5/10/15 etc. degrees into wind (can you fly to 1 or 2 degrees?) and there's your heading. Then GET GOING and work out your ETA once en route. By far the most common debrief point I have for people concerning diversions is the amount of f***ing about they do before actually setting off on the div. It's not a precision exercise, you just have to get there (without totally gashing it).