my findings are the following.
You can have people putty for cheap and edit efficiently heads.
that is almost 80 percent of the job, since heads are the most important part of the body (because the motion of the mouth, eyes).
The problem is that haptek stop his effort there.
Ok they sell what they call half-body and some tools to (almost) manage them at in incredible high price. (3500$ for 2 half-body).
The bad news is even if you got the money to buy the kit, it is pretty useless, because body and half body are not made from haptek, but build from a 3d application (maya, 3ds, animation master), so you still need to spend a lot of $ and time to get one of these product work for you.
This is a pity, since i realize after few search on google, that there is a lot of torso and body available on the web.
You just need to find a page displaying an haptek character, view the html code, and get the url for the .htr file and save it on your disk.
At the same time, with same method, you can capture enough .hap mood script to get a pretty complete library of behavior for moving the character. and if you need to create your own hap, you still can refer to haptek free guide, that list all the commands/query available.
This make the 3500$ for a bunch of utility and 2 basic torso looks even more ridiculous, since all of this can be found for free and should cover most of your needs.
Additionally , creating your own body or half body seems not a good idea, since you need to create all the parts (bones, joints, anchor points) in a way they stay compatible with the accessories or the movement files (.hap) , or else you could end up being forced to recreate everything by yourself, especially if you want a lot of different movements with arms and legs.
So currently the situation is pretty clear.
Buy People putty, hack as many standard characters and accessories from the web and limit you changes to "skin swapping" or "wig swapping"
To answer to you question, it seems you would need the utility from haptek that let you calculate the difference between a standard head and a custom one and apply this file to a standard torso.
I am afraid that still require the use of maya or 3dstudio.
Frankly the product is so good and powerful as it is, that it does not worth to bother of spending so much money or time to make small change.
Better to use this energy to implement it properly into a web page, master the TextToSpeech/emotion feature and create a nice stuff.
If you visited the pages from the companies working with haptek torso or body you will find they are all using the same standard characters.
