I had to do this recently--and I posted about it recently as well. I had a personal trip that included a round trip from DCA-JFK (and then a separate itinerary on Iberia to/from MAD) and then needed to go to Chicago for work. I booked a ticket through our work portal from JFK-ORD (and then separate itinerary return ORD-DCA). After I took the first leg of the DCA-JFK trip I canceled the return flight.

It looks like I'll have to do it again because of another work trip coming on the heels of a personal trip.