It is super simple if you can handle a pair of scissors and the occasional electric shock - see my reply to Cynikal above.

Get some EL panel - cut it to the shape of your seatpost - get out the sellotape and insulate the edges - wrap it around your seatpost (I made a tube that can be slid on and off when the seatpost is taken out of the frame) - plug it in - ride around the streets like you are in Tron