No, using the shape will cause there to be an overflow in the objects AABB calculation, and then bullet will remove it from the simulation. At least...thats what happened the last time I tried it. You want to look at collision flags on the btCollisionObject base class:http://bulletphysics.com/Bullet/BulletF ... bject.html
Look at the enums near the top, in particular "CF_NO_CONTACT_RESPONSE". Get the existing flags and add that flag to it, and then pass it in to "SetCollisionFlags(int)". Should look something like this(taken from my trigger object code):
Ghost->setCollisionFlags(Ghost->getCollisionFlags() | btCollisionObject::CF_NO_CONTACT_RESPONSE);
In some cases people have reported that not having any effect, which I'm not sure what that is about...I've never had issues. Good luck.