How to track E-commerce values on a 3rd party site

[grafx77]

I have thoroughly read over the information on Google Analytics website for tracking e-commerce values on 3rd party sites, but there is alot of overlapping information that just doesn't make sense to me.

1. The tutorials tell you to post this script on your website and the 3rd party website:

 P class=MsoNormal style="MARGIN: 5pt 0in; mso-pagination: none; mso-layout-grid-align: none"SPAN style="FONT-SIZE: 10pt; COLOR: gray; FONT-FAMILY: 'Courier New'"<script src="http://www.google-analytics.com/urchin.js" type="text/javascript">BR</script>BR<script type="text/javascript">BR_uacct="UA-xxxx-x";[/color]SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'"BRB_udn="none";BR_ulink=1;/BBRSPAN style="COLOR: gray"urchinTracker();BR</script>[/color][/color]

Ok, but how in the world are you supposed to get the 3rd party website to post this script on all their webpages? Do you only get them to post this script on their confirmation page?

2. There is another script you post on your links going to the 3rd party website that looks like this:

 P class=MsoNormal style="MARGIN: 5pt 0in; mso-pagination: none; mso-layout-grid-align: none"SPAN style="FONT-SIZE: 10pt; FONT-FAMILY: 'Courier New'"<script type="text/javascript">BRdocument.write('<a href="javascript:__utmLinker(\'https://www.merchant.com/?store=parameters\');">Purchase Now</a>');BR</script>BR<noscript>BR<a href="https://www.merchant.com/?store=parameters">Purchase Now</a>BR</noscript>?xml:namespace prefix = o ns = "urn:schemas-microsoft-com:office:office" /o:p/o:p[/color]

Ok, so where do I enter in the parameter that will report the total_cost of the sale back to GA?

Any help is greatly appreciated........thanks in advance,
John