This is an idea I came up with after reading for a while and using Honor buddy quite a bit.
First few things you should know, or at least what I've heard on forums. Not 100% sure if some of them are completely accurate.
First, from what I have heard most of the time when you are banned it isn't a battle net account ban just an individual account ban. With that in mind lets continue.
Second, since MoP came out achievements have become account wide, meaning all honorable kills go across all accounts. Moving on.
Thirdly if you create a free trial account you will still get the honorable kills on your other accounts under the same battle.net account. But if you read the forums under technical support Trial/Starter Account Removals - Forums - World of Warcraft it states that you can remove trial accounts by simply submitting a ticket.
***NOTE I'm not sure if they will if it's banned or not***.
That is all there is to it, this will let you get the of the Horde or of the Alliance achievements, or even Bloodthirsty.
P.S. I don't think this is a repost I did search for it but I found nothing, also this is the guides section so I was not sure to post it here or in the bot section.
*EDIT*
I am currently testing this idea on my own, since you will only be able to get to level 20 the honorable kills will slower than they would at 90. Also I'd suggest getting heirlooms with the honor you'll get so you can get even more honorable kills.