Using macro to change colours


Our preproduction team are having issues with different blacks in a file before print. We want to be able to run a macro that can go through a file and change all 100% black objects/ outlines etc from C:100 M:100 Y:100 L:100 to C:0 M:0 Y:0 K:100. 

Is this something to record myself or does it need a written script?