(My reference of being right-handed is referring to my dominant hand, while my left-handed releases are from my non-dominant hand.)
When I started working on throwing left-handed backhands, ha, it was scary ugly. That disc would wobble through the air and my target zone in front of me pretty much included a 180 degree field of landing and anywhere from 3 to 15 uncontrollable feet! No one was safe.
Needless to say I was having a very hard time trying to learn being left-handed with just my backhand release, never mind any other release. But then I hit on something that really helped me figure out throwing left-handed, for no matter what the release.
I started focusing on how it felt to throw a shot in my right hand and then tried to replicate the throwing motion and feeling in my left hand. Sometimes I'd try a regular speed shot with my right hand, but then, I noticed that sometimes, making the shot slower with my right hand helped my translate the motion to my left hand.
For example, I was working on left-handed backhands, so I started simulating slow right-handed backhands, feeling how it felt in my right hand, and then trying to replicate the motion and feel with my left hand.
This helped me immensely come up to speed on all my throws with my left hand a lot quicker than my trying to teach my left hand what it needs to do.
But keep something in mind... that even though you can start replicating the feeling of a throw for your non-dominant hand, it will feel awkward for a very long time. Even when the throws look good, it still feels awkward to toss a shot. I just ignore that I feel like a lumbering oaf and just execute!!! I did not shake that awkward feeling for quite some time. I chose to ignore how it felt and focus on how the shot looked.
That helped me get past the initial issues. Now I can toss a lot of my shots both left and right handed and just enjoy the process.