Well if you have created a binary that acts as a DCE device, packaged it, and defined a Device Template that uses that package to install the device, then you have done everything except actually add the device! In other words, you are prepared the system to make your DCE devices available, should someone want to use them - ie the Device Template is there - but you haven't actually told LMCE to create an actual Device instance from the Device Template.
There are 2 ways you can do this - automatically using pnp, or manually through the admin site in the devices tree. Ideally, set up the pnp system - you can see the pnp stuff towards the bottom of the Device Template. You need to pick something that you can use to identify the device with. So for Ethernet you can choose the MAC address range that the manufacturer has been allocated, USB you can use the product/vendor ID, etc... The rest of the template definition will define where the device gets created and the package to install when it does. pnp
Otherwise, you can just go to the correct parent object in the Devices Tree, and use the Create Device (I think) link. Then choose your template. This will create the device. You will then need to reload the router. At this point, assuming that the device works and the template indicates that it implements DCE, the system will launch the device on each reload.