I am not familiar with Canadian law, but here in the US, the answer is ... maybe
If the modem can be made to pass data using one of the recognized modes, and within certain limits as defined in Part 97 (without encryption, within certain bandwidths and using modes available to the general public..)...maybe
However interesting that exercise might be, there's lots of easier ways to do this. Airmail is dedicated to use certain modems, AFAIK, while PSK modes could be sent using a handful of parts, depending on what radio(s) you are using.
Here is Airmail's home page...
The Airmail Home Page
Mike