I still think the electronic recirc is the best method. Has the scale and axis you want.
N249 won't have the current capability to drive the pump, so use a MOSFET or a relay. Pretty simple.
There is no failsafe to set back your timing maps or reduce boost when the meth is not working. It may work, but it is far from ideal... The way fukenbroken describes is much better, just not as plug n play for most...