Well ike said in the manual i can create a Capsule shape
for my character :

ENTITY* shell_right = ent_create("shell2.mdl",vector(-40,53,40),NULL);

pXent_addshape(ceiling, shell_right, PH_CAPSULE);

Ok it's create automatically,
but to avoid a charatcer to have it's foots floating on ground :
It would be cool if we could tweak it or change the center of gravity, for example move it a little up and decrease the size, !

Well i have the solution :
The character model will always follow the cpasule physix,
Caus it's attached to it in some way.
I just have by code to move the character a little down after the physic engine have moved the capsule.

But for changing capsule size, i don't see ?
Perhaps after creation, getting the size by code, and manually tweaking it for recreating the capsule with changed dimension ?

I believe you can set up the capsule size through the min_x, max_x vectors. Set the vectors to the desired dimension before creating the shape.

Yes, i think it's the way to go !

I'll try to see if i can make my own visual tool ( in the same way as the visual hitBox editor made by SuperKu ) !

well, I can't get it working:

even with changing the min_z values, my character is still floating above the ground.
I am using a model for the ground, but it shouldn't make a difference?

Try to scale the model (scale_z, maybe even x and y, too) before you set its capsule hull, then reset its scale.

Thank you Superku!
It works!