Need help to convert Fixed % MM to Fixed $ value

Hi all, I have zero experience in coding and need some serious help
I'm using this script (awesome btw) in this thread, but it deals with a fixed % of balance to calculate lot size.
It could be really useful if someone could convert it to calculate lot size based on a fixed $ value instead.

http://www.forexfactory.com/showthread.php?t=281772

thanks in advance
fuzz