How to keep an occupancy sensor triggered without motion?
Many occupancy sensors allow you to adjust the amount of time that they can't see you before they shut the lights off. I'm not sure what model you have, so I can't instruct you exactly how to adjust, but setting the timeout time to something longer would probably save you the trouble of building something to circumvent it.

For example, a panel on this Leviton switch pops off to reveal some adjustment controls.



PDF instructions

If your office is managed by your company or a building manager, it may be worth asking the maintenance guy.