No, this is not possible. Both Authorize.Net and your merchant account do not allow fund transfers.
edit
Unlinked credits are not fund transfers. They are refunds which are not tied to a specific transaction in Authnet's system. They are not allowed to be used for fund transfers by both Authnet and your merchant account provider (as per their contract). If you do fund transfers this way you will get your account shut down and be banned from accepting credit cards by being added to the match file.
Once again, this is not a fund transfer and is not allowed to be done as such.