This is my first LoRA release, so lower your expectations. It will probably alter face, style and other things.

Focus on NSFW images of facehugger with proboscis inserted. Example prompt:

facehuggerback, facehugger with proboscis in vagina, on ass. 
woman lying on stomach with blonde hair, large breasts.

It's trained on terms describing the facehugger view, e.g. facehuggerside or facehuggerback but these don't seem to add much to the final result. The position on waist , on legs or on ass will mostly be automatically done when you describe the character viewing angle.

I got better results by first describing the facehugger, and then the character.

It's trained mostly on images in vertical portrait from illustrij (https://civarchive.com/models/1025051/illustrij) like 1040x1510, so I expect that will generate the best images.

It also seems to work great with other insects, give it a go and please share all your cursed content!