ACTUALLY THT, it is possible.... Using ODBC connections in the control panel, it should be very possible to 'trick' dkserver.exe to thinking its connecting to a MSSQL database, while in reality it is connecting to a MySQL. Also, check out this link:
Mysql DOES support stored procedures, just no one has taken the time to rewrite all the ones in the dekaron databases into mysql code.
NOW! Back to the original question, you can either host the server on a dedicated server, and give login information to both of you. Or, have him run his computer 24/7 with port 1433 open and create a remote account on YOUR machine in Query Manager, with HIS IP address and database name in the form of "123.123.123.123\\MSSQL-SERVER" with the proper login credentials. Then you will be able to run remote queries and stuff from your machine.
Give this a look as well, the first post explains it pretty nicely:
Any other questions?