While in ASE, try going to file, then download latest filters. I'm pretty sure that ASE has the latest DC mod included. If not, then do this:
Go to "filters" then select "new".
In the filter editor where it says "name", type: desert_combat
In the larger window below, type this in:
1 if gameid ~== "desert_combat" goto 3
2 remove
3 if ingame ~== "*bfield1942" goto 5
4 remove
Click "ok" then you should see a new folder in the "my filters" index in the left of you ASE window. Select the desert_combat folder, then right click on it and select "custom config"
On the custom config window at the very bottom, you'll see the listing "Cmd Line".
In the Cmd Line, type this in:
c
program files\ea games\battlefield 1942\bf1942.exe" +game desert_combat ( or whatever drive letter the game is stored ).
Click ok, then you should be set. I don't know if that would give you a DC mod only listing of servers, but I it will allow you to play it through ASE. If you have the DC filter update from ASE, just click the folder in the BF 42 mods listing and refresh and that should do it.