It is possible.The Leslie 710 has two channels - the rotary channel for the flutes and the stationary channel for orchestral voices. The Hammond A, B and C - series are one channel organs and usually connected to one channel Leslies - eg 145, 147 and 122. You can connect the 710 using the rotary channel only. Or you could install a frequency crossover that diverts the lower frequencies into the 710's stationary channel. It would be good for the Rotosonic speaker to escape the lower frequencies. The speaker is just a crappy 6"x9". Another way to utilize the 710's stationary channel is to divert the A100's reverb signal into it. Apart from these considerations I can't see any problems doing it. That's the way I see it. But don't take this as gospel. I'm just a Carpenter and when it comes to electronics I get it wrong sometimes . I'm sure the resident experts will chime in. And there is plenty of info on the net to guide you.
As a matter of fact I've been thinking of hitching my two L710's to my C3. But this is low on my list of priorities.