JW,
EJ (or now NG) can do this. What it will NOT do (as I stated before) is full demand/supply linking. But it WILL do what you just asked.
If you do not want to move to NG, then there are scheduler programs out there that you can link to DBA through ODBC, but it will then only give you the information in the scheduler program. If you want it to write back the changes to DBA, you would be looking at SIGNIFICANT dev cost to write the code to do so. Quite frankly, after you would get through paying for the scheduling software, AND the dev time to link all the information through ODBC just to get the required data into the schedluer software, you might be rather disheartened to then fork out AT LEAST that much again to be able to write the changes back to DBA.
Plus.....it's gonna run slow!

(a LOT of data that has to go back and forth to make something like that work).