mixing boehm allocator with other allocators

Hi,

I want to use a foreign allocator together with boehmgc:

template<T>
class X:public boehmgc::gc_cleanup
{
    T* mem;

    X()
    {
        mem=alloc();
    }

    ~X()
    {
        free(mem);
    }
};

where X is allocated via boehm's allocator methods.

Will this just work is is this asking for trouble?
If T contains pointers to objectes allocated via boehm's allocater, will
they be properly collected?

Thx,
Alex