Discovery ABS Modulator

On a 2002 Discovery the dealer informs me that the error code of 11,4 is appearing. They cleared it and it hasn't returned but they tell me the modulator needs to be replaced.

Is this something that I can replace myself or are there specialized tools/systems that need to be used?

I have done alot of break work from rebuilding master cylinders to replacing all the lines but have never worked with an ABS system?

Any help would be appreciated.

Thanks