ok here is my word of advice. you dont want the cart and dolphin sharing a login. you can read all about that over on OSC. but its your site, do what floats your feathers.
at any rate, integrating anything into dolphin is quite the feat, as you can see there are very few integrations, specifically when it requires cohesive co-functionality between dolphin and any other xyz script. there have been attempts, and there have been failures.
now onto oSC and CRELoaded integrations and the possibilities. I have a contact I will share from commercexp.com. the contact is van michael. so go to commercexp.com and shoot them a support ticket, and specifically request van michael. i dont think you are going to get anywhere in the dolphin forums where OSC or CRELoaded are concerned. that would be like going to e107 and asking them to integrate raychat into their CMS.
at any rate, good luck, and happy hunting.
When a GIG is not enough --> Terabyte Dolphin Technical Support - Server Management and Support