Hi Cal Girl,
Yes, your friend can certainly accomplish this. All he/she needs to do is sign up for an Auctiva account and generate an eBay token.
Once your friend has done this, all of his/her current listings will be imported into his/her Auctiva account and appended with the store window within about 12 hours. When he/she posts future listings, they will typically be appended with the Auctiva store window within about 6-8 hours of being listed directly through eBay or through another listing service.
-Mike