I installed a Signaldynamics Back Off brake light signal module XP several years ago. I have two brake lights, this module is connected to the lower one.
The XP model, which is for incandescent as well as LED lights, or a combination of both, also has an optional circuit - the instructions state it can be used for "Emergency motorcycle flasher or car back-up light"
I use this circuit for the same taillight, but have it on a direct power supply from the battery, with a hidden switch. The ignition does not have to be on.
However, Signaldynamics does have a disclaimer - the XP module is rated at 10 amps, suitable for only three 1156 or 1157 bulbs.
To be on the safe side, if you wanted to use this for all your signal lights, I think you would have to have LED signal lights on your bike.
Do you want your signals to flash as an emergency option, when the bike is stopped, or when on the road driving ?(I suspect that may be illegal in some states and provinces)
If you want flashers for emergency use only (busted down on the roadside), you could do as I did - wire your brake light, and also use the module to feed another red light located on the front of the bike. Of course flashing red lights are the universal sign of breakdown, and would not be confused as flashing signal(yellow)lights. Hopes this makes sense. I'm starting to confuse myself!
Cheers!