Well that was an easy answer, but, if it is using LDAP calls, it should work.
The schema would need to be extended and perhaps some setup of the DIT, but it is "just"

LDAP, Right?
And if it a MySQL server, then it is just SQL, Right?
So it should work.
And I would bet that the product would appeal to more organizations if there was this type of integration made available.
Thanks
-jim