The cable has just gone on my 1999 scenic and I removed the panel without a manual to refer too. It's quite straight forward, just take your time and don't use too much force.
1. Gently prise off the small triangular cover at top left (wing mirror). This just pushes on but the connectors are quite long and one of my snap during removal.
2. Pull off the wing mirrow control knob and use a small flathead screwdriver to remove the plastic base.
3. Unscrew the door release handle (note - this screw is slightly larger than the others).
4. Unscrew the door pull / window switch and use flathead screwdiver to prise upwards.
5. Disconnect the electrical connectors, making sure you know what goes where for you reconnect. If you dont have enough cable slack to do this it can be removed once the door panel is lose.
6. Remove screws from the bottom of the door panel.
7. Prise off the speaker cover, remove the four screws retaining the speaker, pull the speaker up and out then disconnect the speaker connection.
8. Once all the screws have been removed the panel is held in by clips - starting at the top right of the panel carefully insert a flathead screwdriver between the panel and door (taking care not to scratch the paint work) and carefully prise apart working your way around the door. You will find there is a dark putty that acts a seal, which you can leave and reuse when replacing the panel.
9. Feed the door release through the panel and reattach.
Hope this helps.
Pete
September 2008