There is no generic way to turn a power toggle into a discrete.

You can decode the toggle (IrTool and DecodeIr) then use MakeHex to generate the full set of 256 signals and test them to find a discrete code if it exists and you just don't know about it. But you can't create it that way if it doesn't exist.

It's possible that the device uses different rules for checking the validity of a power toggle when the it is off than when it is on. So you might find a fixed duration signal is long enough for one but not the other, or maybe unrelated garbage IR just before or after the signal will stop one from seeing the power toggle, but not the other. Or maybe a legitimate other command immediately before a power toggle (in the same pronto hex string, not a macro) would cause the device to be too busy to see the power toggle if already on, but it would ignore the other command and then not be too busy if off.

With a good understanding of Pronto Hex and lots of nearly blind experimentation you might be able to invent a power discrete where none existed.