Hi elordik, that's an interesting question!
You can't transfer ended or currently running auctions to another account, but if you just want to pick up past auctions from one account to re-list with another account that should be possible.
Here are a couple of ideas that could work:
Use software or a web-based service that supports multiple accounts and allows you to re-list auctions from one account to another account. Start using a package with your old user account, pull down your past listings, then change to your new account and re-list the downloaded auctions. Many of the high-end packages support multiple accounts, but you would have to research further to find out if they supporting re-listing across accounts. I'm thinking of services like
MarketplaceAdvisor Premium,
eSellerPro,
Infopia,
Laris,
Zoovy etc.
If you are looking for something lower cost you could investigate
AuctionSound,
inkFrog,
Vendio (web-based); or
AuctionSage,
AuctionSplash,
eBay Blackthorne,
SpoonFeeder (desktop).
If you want zero cost maybe
ChannelMAX or
Auctiva will do what you want.
Hope that helps