eBay would have to change their site first.
All eBay allows for choices is:
PayPal
Money Order / Cashier's Check
Personal Check
Other / See Item Description
Visa/MasterCard (through merchant acct)
Discover (through merchant acct)
American Express (through merchant acct)
And then they have box for "Payment Instructions" where you can provide details (which is available in auctiva)
Auctiva does have where you can put more info in description area of listing with a header (in addition to the above options). such as:
This is available through the Seller Details in the profiles area of Auctiva.