Hey, I am thinking about the same idea.There are two echoes which can emulate the Rigger, as posted by Michael - "Skinlink" and "Machine Mind".
"Skinlink" gives you DNI connection to an object ( I imagine that if a vehicle has Rigger adaptation it can be connected to and thus controlled. )
"Machine mind" gives you the qualities of a level 1 Control Rig, which essentially means that you can jump into a vehicle or a drone and you get +1 bonus dice for all vehicle/drone skill tests and bonus point of Edge.
There are two complex forms which I think are useful for controlling devices. "Puppeteer" and "Emulate"
"Puppeteer" allows you to take control of a device even if you don't have the admin access to it, thanks to "Control Device" matrix action.
"Emulate" lets you run a single program, including autosoft.
Combining it with "Focused Concentration" quality which allows you to negate -2 dice pool penalty for sustaining multiple complex forms, you can highjack enemy drones, or simply enter yours.
Finally, "Machine Sprite" can override a machine on autopilot and take control of it.
So I think that Technomancer has already built-in tools to emulate a Rigger. And I can imagine way better usage for the stack of ¥NuYen needed for a decent RCC
Technomancers do not use electronic devices or programs. They are the device...