Some (read: very few) print drivers will allow you to create page ranges within a job, and apply different settings (such as BW or color) to each range.

This is normally found on much higher end machines.

If there is a Fiery involved, you may be able to send a job to the hold queue, then create the page ranges in Command Workstation (although it may require an option).

There may be third party software out there that would do this, but good luck on wading through the swamp of stuff that's out there. Yuck.

Sorry, no easy way to do this, let alone cheaply.