Jennifer, I applaud you for trying to make sense of a confusing situation.  BUT:
 I think it is a mistake to create a protocol for the use of something that should actually be avoided, even though you are trying to set reasonable guidelines.    You would not write a protocol, for instance, saying when it is okay not to use a car seat.  

As a hospital, we do not have protocols regarding alcohol use by moms, as we do not give the alcohol.  Hospital or institutional protocols refer to the practices within the institution.  Our suggestions for life beyond the institution are guidelines, not protocols.

Even as guidelines, anything you put down on paper makes you liable, if harm results. Further, the minute you call them guidelines for use, the recipients can and do start adjusting your parameters to their own beliefs and needs. 

I am of the camp that believes that it IS okay to drink occasionally, but I think it is almost more dangerous to define occasionally, than to leave it undefined.
If you set a guide that mom thinks is too seldom, then she will not necessarily want to listen to the rest of what you have to say.   But I do think a  couple of drinks a day starts leaving room to infer there is a drinking "problem."

If you must continue with this plan, I would strongly suggest that you start 
it with a disclaimer that you do not RECOMMEND moms drink, and list the
 possible ramifications of drinking and breastfeeding (like the potential for 
decreased milk supply, especially if mom skips feedings and doesn't pump 
in their place).   If moms want to take a drink, or several, they should bear 
in mind that alcohol leaves breastmilk at the same rate that it leaves mom's 
body.    She should plan not to BF her baby  during that period of time, and
 to discard milk expressed during that time.  She should further make sure 
someone else is available to be aware of and tend to the needs of her baby,
 especially  if she plans to drink beyond her personal tolerance (like at a 
wedding).

I realize the irony, here:  I am telling you, on the one hand, "don't write this 
protocol."  And on the other hand, I am suggesting approaches to it.  I 
understand the challenges of nursing school, and I know it is probably too 
late to decide on a new protocol, but I hope you will remember what I am 
saying when you go out to the world-at-large, where there is no publish-or-
perish pressure.

Sincerely,  Chanita, San Francisco