Hold the desktop microphone stand by the goose neck and rotate the base, unscrewing it completely. Remove base, leaving just the flexible goose neck, with a standard microphone clip at one end, and an exposed thread at the other.
Drill a hole in one of the gripping tabs of the clamp. Drill the hole directly in the centre of the clamping surface. Too close to the edge could leave it too weak to support the microphone.
Insert the threaded portion of the goose neck through the hole drilled in the clamp. Secure the base of the goose neck to the clamp by tightening the microphone-stand locking nut. Microphone stand fittings use standard sizes, either 5/8" or 3/8" so a locking nut from an old microphone stand should fit the goose neck thread without any issues. If you have one of each size, use a thread adapter to convert it.
Cut or file off any excess thread from the other side of the clamp. It is important that the bolt does not obstruct the gripping surfaces that the clamp will use to hang onto the bass drum. With all the pieces assembled, attach the clamp to the raised rim surrounding the edge of the bass drum.
Insert a microphone into the standard clip. The goose-neck will allow you to position it wherever you would like in relation to the front of the drum.