I just tried to pair a TRÅDFRI wireless dimmer with the Hue bridge and a Hue plug, but did not get it working. The Hue plug was controllable from the app, but the TRÅDFRI wireless dimmer was unable to control the Hue plug.
I tried it again, but instead of the TRÅDFRI wireless dimmer I used a TRÅDFRI on/off switch (and also a TRÅDFRI remote control). They worked fine with the Hue plug and a Hue bridge.
So it looks like the TRÅDFRI wireless dimmer is incompatible with the Hue plug, unfortunately.