i dont know about an outboard, but i know you can for an I/O with throttle by cable, pretty much the same concept right? i dont see why you couldnt, email perfect pass, hey will have an answer for you pretty quickly
I think you could do it with some of the electronic throttle control models but I doubt there is space to add a servo if it's mechanical. I don't know if anyone has the interface to control the engines already built.
I haven't done a Yamaha four stroke outboard before. If I had a photo of the engine with the cowling off showing the throttle at full throttle and at idle I may be able to suggest if it might work.
Would you be prepared to dedicate 16 hours of playing around with the installation? Are you handy with tools and can make a few basic brackets etc?
PP is awesome and works great on outboards but your installation will be a world first and it is harder on Yamahas in general because of the push throttle configuration.