No, you'd have to use the LCD (or a hard button).

But honestly, you don't have to do that. Getting the power set up correctly isn't difficult at all. What is it doing (or not doing) that's causing problems? I guarantee someone can tell you how to fix it in just a few minutes if we know the problem.

Assuming the power command in the harmony command list works, the only issue is whether you have the power control setup as a discrete (separate buttons for on and off and that's all they do) or a toggle (one button that toggles the set on and off). Once that is setup it will work. If it doesn't, try increasing the inter-device delay for the device that isn't working - it's probably just missing the on or off signal.

If you want to leave a device on when switching activities even though it's not in all of the activities, check the "leave unused devices on" option for all the activities. Or just add the device to the activity as a passthrough.