I actually had this come up last weekend at the APA national tournament. There was a guy that drew a black line down his ferrule to sight. Which is permissible and was explained as it no different then using a Meucci cue that has have a red or black dot for sighting.
I personally am not familiar with Meucci so I can't confirm or deny that.
I don't think the Meucci dot relates to aiming. It is at the joint and you can't see it anyway when shooting. It is to orient the grain of the shaft the same way every time.
The ferrule on the other hand is in your line of sight.