Just needing to process fixed amounts.

Im reading up on the documentation and checking out the
examples .. it
seems google has provided examples for all the major server
side
languages except for 1 - coldfusion.

Im a web designer and would like to offer a link at the
bottom of my
pregenerated invoices "or pay me via google
checkout"

I just need to pass a single amount over to google and
process that.

I see that checkout is very much oriented around product
delivery /
shipping tracking. These parts of the process are not
relevant because
the only people that I plan on having pay me are basically
just coming
to pay an invoice for work already rendered.

Can someone give me an outline of how I go about this?