You CAN throw for yourself with one of the red plastic throwers. I have done it several times. It's pretty darn awkward, and you have to pay careful attention to safe gun handling, and you'll only be taking longer shots, but it can be done if you've got no one to go with you.
I hold the shotgun in my left hand (weak hand). Throw with my strong hand (right hand). Then drop the thrower, mount the shotgun, flick the safety and shoot.
Probably not very good training, since you'll not be holding the shotgun the way you would be in a hunting situation. But maybe a bit better than shooting stationary targets, if that's your only other option.
I would like to find a throwing machine that I can operate by myself and still shoot.