in /etc/rcS.d or /etc/rcX.d (X is your runtime level, most likely 5) you can edit one of the startup scripts by adding the command to the very end or make your own script. For example

in /etc/rc5.d create a file (S99disabledma) and put the following in it

#! /bin/bash
hdparm -d0 /dev/hdb
hdparm -d0 /dev/hdc


then change permissions so it's executable - chmod 755 should suffice