V2 is a LOHA model so you need the Lycoris Extension for A1111 to use it (only for A1111 Version <1.5). For Automatic1111 version 1.5 and higher, no extension is needed. Lycoris models work exactly the same as LoRAs on 1.5+. Install them to the LoRA folder and they will show up in the extra networks section, just like other LoRAs.
Bettercocks2 is Identical to Tgirls_V4.
Version 2 is a huge improvement over V1:
Can create flaccid penises in almost every pose
follows prompts much better (large/small or flaccid/erect)
better looking penises
much better at side poses and poses from behind
added concept of penis bulges
The Model has been trained on and works bests with epicRealism V5 (https://civarchive.com/models/25694/epicrealism). epicRealism V4 and V3 work great ass well.
Other realistic Checkpoints and even Anime models should work, but the result is almost certainly going to be worse.
General Tips:
The recommended strength is 0.5-0.9, a higher strengths sometimes creates more realistic results.
The model seems to follow size and state (erect/flaccid) better if they come close to the beginning of the prompt
size and state (erect/flaccid) works better if the prompt is shorter
Use highres fix!!! The upsampler does not really matter. Denoise should be at least 0.3.
Use the regular model for impainting penises. Select "only maske" set Padding to a >50px and set denoiseing to ~0.6
Look at the samples for prompts
CAUTION: as is was initially created to create Tgirls all women in you images will grow a penis :D.