How do you tap off of a 480 volt disconnect?

You don't. You hire a qualified electrician who doesn't need to read this page for the answer.

That said, if you are merely curious as to the methods:

"480" Volt will be 3-phase with either Delta wiring (480 phase-to-phase, NO neutral), or Wye wiring (480 phase-to-phase, and 277 phase-to-neutral).

You can use this directly, to run three phase equipment from all three phases, to run equipment at 480 from just two phases (being careful to keep loads balanced), or to run lighting circuits from the 277-to-neutral (being careful to size the neutral conductor carefully).

You can also step it down to "208", which will be 208 phase to phase and 120 phase to neutral -- "standard" line voltage.

But seriously, if you need to ask the question, you SHOULD NOT be touching 480 switchgear and wiring, for the safety of both yourself and others.