There are no stupid questions - only stupid answers, so be prepared
I may not understand your question properly, but this is my input :
Yes you can use as many battle.net accounts on 1 pc as you like.
Even at the same time using different WOW installations (you are not supposed to use the same WOW installation many times in parallel-sessions).
To start, buy a 3-license Honorbuddy account and create three separate WOW (Battle.net) accounts.
You do have to buy three separate WOW installations as well (see my remark above).
And yes, you can use any account on any WOW installation on any PC.
Having said this .. do not think that will make it safe for you to use HB.
Botting is never 100% safe.
Happy botting
PS
What the other respondent (thatwouldbestealing) said is true : you can also manage your sessions from another PC by using Teamviewer and the likes.
But I don't see how that would make your botting safer .. IMO it has no impact on your "visibility" to Blizzard.