how can i recode my megane 96 key fob?

i recently changed the battery in my only megane '96 key fob and now it doesnt work at all. i went to most garages in my area and they advised me to go to a main renault dealer, so i did. they told me it i could have a new key and they recode it. the price for this to be done was £160 and a wait of 5 days. i realy cant wait that long as entering the immobilizer code every time i need to start the car witch baring in mind i work in it so every 10 mins or so can be quite time consuming and annoying. so please is there any way i can fix the key myself? thanx