I use this, and some might find it worthwhile to add a Manual Reset sort of switch, in the event you press your Cadence Hotkey while in the middle of a GCD, then you have to wait 2 seconds before casting it correctly.

ISBoxer Hotkey: Shift 2 (or whatever)
Step 1: Set Mapped Key Step Action - <Cadence's Mapped Key> - Set to 1 on all
Step 1: <Activate Cadence's Mapped Key, so it performs Cadence and then advances>