You can create a check to a non-vendor in both ACCPAC Plus and in Adagio by leaving the vendor number blank when entering a manual check transaction. Although it prompts you for a "cash invoice number", the transaction is not saved, except as a check in the check rec file.
The detail that needs to be entered is the GL distribution detail, not the invoice detail. If you want invoice detail, you have to set up the vendor and record the invoice first.