conditional field/group after a taxonomy hierarchical menu

Hello ,

I'm building a classified ads website , with ads category ( so taxonomy...)
So, I had created a hierarchical taxonomy for category, for example :
category1(for example cars)
subcategory1.1 ( for example camping-cars)
subcategory1.2 ( for example pick-up)

In the AD content type, I'm using hierarchical select module to lookup into taxonomy vocabulary in the form.

It works fine...

BUT :
After the hierarchical select of a category, I want to show a conditional group of field , for example, if the user select cars-pickup category, I want to show a special car form (which is a group of cck field..like year of the car etc....) ......

I had tried the conditional fields module but It works only with a CCK controlling field...not taxonomy ...

So How can I do ?
I'm really looking for conditional fields/group with TAXONOMY controlling field

Any help would be appreciate !
Thanks to you,
Christophe, from France.