My Model of DNS-323 had 12vdc on one side of the push button 
switch and when depressed it applied 12vdc to the other side of the switch.

Evidently there was a vesrion of 323 that used ground at the switch.
However mine used 12Vdc as stated above. Therefore I had to insert a relay 
as shown on the schematic.

If your swicth uses the ground then the relay is not needed just connect
the output of the 2n2222 to the switch. Check before you begin.

I hot glued the relay and the MOD board onto the DNS-323 board and insulated 
them from the DNS board with double sided sticky tape. If your 2n2222 is a 
metal can "like Mine was" then just dap a glob of hot glue on the can and 
kool it fast so that it doesn't run all over and this will insiulate it from metal.