The easiest and quickest way is to remove the bogie frames as shown below in DSC01157.jpg or to strip the whole loco and remove the whole bogie as shown in DSC01160.jpg. I've done this work to improve the original class 66 electrical pickups for DCC sound.

The Above Image shows the 1/16" x 0.005" x 6" Phos. Bronze Strip from Slaters soldered behind the existing pickups.

The Above Image shows the strip cut to length bent and completed

Above shows how I've wired the loco for directional lighting.

Hope this is of some help.

Regards

Mr B