How to share existing PC docking-station-like setup with Macbook Pro
At a minimum, I want to be able to quickly and easily switch between
  using the monitors, mouse and keyboard, between the PC and MBP


You can't if your peripherals/accessories are plugged into this docking station.

The dock connects to the HP notebook via a proprietary connector.  There's no way to connect anything but the supported notebooks to this dock. 



The key here is to understand that the HP dock is not an "independent device."  It's designed for convenience when wanting to use desktop peripherals (mouse,monitor,keyboard, LAN, etc.) with your notebook; consider it part of your HP notebook when docked.  

To share devices, you need "something" that interfaces with the peripherals that can be connected to both machines.

Your only options are to:


Ditch the dock and use a generic USB hub/dock and manually move the USB cable between computers
Get a Bluetooth mouse/keyboard (like the Logitech MK850) that supports multiple devices (won't support video switching)
Get a quality KVM switch that supports multiple monitors