All the advice is above is spot on. I had to do it when my Troll door fell off and the fix worked a treat. The only variation I used was to use Evo-stick wood glue - the white PVA based wood glue - and so I had to wait 24 hours before I could re-screw everything together. In reality I acutally waited a week before screwing as I wasn't using the van for a while so the glue must've hardened off a to perfection. I used wood glue in the assumption that Hymer had the decency to use actual wood in their wood-look doors.
Mind you...not that we should have to be doing these fixes on nearly new vans. Grrr!