write the Qiskit backend class, (and job and provider classes which defines how a normal Qiskit program is converted and send to the backend (e.g. creating a .qasm file and then putting it in a JSON, sending it to the REST API of the back end).
setup a REST API to listen to the requests of Qiskit using this back end, and fill out the logic of running the .qasm file on Qaintum
return the results in an appropriate way to Qiskit