Formula to customise this script pls

I have managed (1hour) to get this script running on my site (off the shelf)

http://javascript.internet.com/calculators/airport.html

in my page http://a1rport.com/prices.htm

Can it be modified to do http://a1rport.com/prices-lhr.htm (i know its a mess, especially in firefox) ie

Heathrow to London = £20
Airport Collection = yes/no if yes add £8 if no add £0
Saloon/Sedan = yes/no if yes add 25% if no add £0
Estate/Station = yes/no if yes add 25% if no add £0
etc
Thanks for any help/sense.

ps how do they calculate the distances and are they accurate, thanks

Jerry