I saw that, but it doesn't seem to implement any of the indexes you'd need in order to run a bloom query efficiently.
That being said, if you stored your bitvector as an array of powers of two, then it would work. But that would be horribly inefficient in terms of space usage.
Which is why PostgreSQL is scriptable: the various contrib modules are often better looked at as examples of how to build your own indexes using GIN/GiST than "this is what we provide".
In your case, though, a strict immutable function mapping the bitvector to an int array as part of a functional index should be sufficient to use the existing contrib module: you don't need to store the things you index in the table.
That being said, if you stored your bitvector as an array of powers of two, then it would work. But that would be horribly inefficient in terms of space usage.