Is there any way I can get to the HTML to edit for my site???

Hi I want to use this product with my site which I have just reworked to make it all CSS instead of tables, now I want to use this cart instead of paypal... How can I easily add it to my site?
Thanks all...

spend alot of time editing the template files to match.. and the css..


then thow the ball and hope the hail mary is complete...

lol

nah realy its jut a matter of editing all the template files.. to match..

but as for new features and release you then may have to rework everything yet agian....