abs ecu

ive just had the bad news that the abs ecu has expired on my 2001 p38. i have managed to get a new one quite cheap but ive never fitted one before. firstly am i correct that its in the passenger footwell behind the carpet on the bulkhead and secondly when fitting it should i disconnect the battery but then have to reset the imobiliser with the key in the door lock?

I have recently replaced mine on my "01 2.5 dhse and did not have to disconnect the battery ,just make sure the ignition is off and it's an easy unplug and plug in.the lights will reset as soon as you start the car.Oh and yes it's under the footwell trim on the n/s

Cheers ill fit it on sat hoping the weather brightens up