Getting access to every antivirus signature database is virtually impossible( those are kept private by av companies, and therefore can't be queried).
The only way would be reverse engineering EACH anti virus product to get access to it's databases, and the hashes would obviously be computed using diffetent algotythms on each product. Therefore, what you request can't be accomplished. And also remember that reverse engineering a software product is a crime on many countries.
I offer you computing checksums of a 65GB corporate virus database, wich i can get in less than a week. By means of some contacts, i could also get access to a 400GB (and therefore absolutely complete) database , but that would take too long to cover a deadline (several weeks).
After getting the databases obviously i would compute all checksums of the virus contained in those and deliver it to you in the requested format.
If you want a list of all malware contained in the 65GB database, just pm me and i'll send you one.