Google Analytics Custom Variables

How hard would it be to record these custom variables after a successful transaction?



_gaq.push(['_setCustomVar',1,'PromoCode','',3]);
_gaq.push(['_setCustomVar',2,'PaymentType','',3]);
_gaq.push(['_setCustomVar',3,'ShipMethod','',1]);
_gaq.push(['_setCustomVar',4,'CustType','Repeat',1]);




Here's the format:

_gaq.push('_setCustomVar',index,'name','value',scope);



Reference article #1

Reference article #2