Yes, you can control dimmer packs with scene buttons on the M260. I've only worked with the Elation DP-415, but I'd bet all DPs work the same way in this respect.
The DP-415 has four channels, one for each of the four power outlets. As you probably already know, if you connect your dimmer pack to the M260 and set it to "listen" on channel 261, when you press AUX 1 on the M260 outlet 1 on the DP will turn on. If you press the AUX 2 button, outlet 2 will come on, and so on.
In the above situation all the AUX 1 button on the M260 is doing is sending a FULL ON (127) DMX signal out on channel 261. When the AUX 1 button is pressed again, it sends a FULL OFF (0) DMX signal on channel 261.
Rather FULL ON and FULL OFF signals, the Scene Buttons can send the full range of DMX signals (0-127)on any channel.
So: Assign a 4 channel fixture to one of the Scene buttons. Note the first channel number for that fixture set by the M260. Set the DMX channel on the DP to receive on the same channel.
Now when that 4 channel fixture is selected for editing, the first knob on the M260 will control how bright or dim the outlet 1 on the DP will be, and the second knob controls the intensity of outlet2, etc.