If you want to use it at prime focus, then you would need to find the size of the thread and pitch of the thread on the objective housing that screws off.
Now, you could simply have someone machine an adapter with that thread on one end, and a suitable interface on the other.
Most people that are buying new today use C mount. This would allow you to use an off the shelf 1.25" to C mount nose for prime focus, or it would allow you to use SLR lenses with the appropriate adapter.
If I were you though, this is what I would do... I would simply put your device back together and use it afocally.
If your device does not have a 1/4 -20 socket, then just hold the device up to an existing 25mm or 32mm eyepiece and look though it. If you don't see much more than you can see with just the eyepiece, then don't do anything, If though, you can see more stars, then you can either invest in a digiscoping adapter like this,
or you can invest in a custom made adapter so you can work at prime focus.
I would try afocal first though. I can tell you from experience that I did not see much improvement using Gen 2 vs a standard eyepiece with a fully dark adapted eye. If you can see more stars though by holding it up to the eyepiece, the next move would be to get a digiscoping adapter and use it afocally and if you are enjoying it, it might be worth getting a custom made C mount adapter.
So, here is what the adapter should look like but honestly, I would try afocal first just to see if it is worth doing.
Misspelled thread on this picture. To lazy to re-do it.
Gen 2 can work OK for NV, but if you use it afocally with a 25mm to 32mm eyepiece and don't see a big improvement, it may not be worth doing.
If you like it, you know what you can don next.