I'm assuming you are talking about the TO part of the message & not the FROM part of the message. There are 2 ways to do it.
I make the SystemSettings BO intelligent in my BSVs. I can then send admin messages to the email address specified in System Settings. Since SystemSettings is always in context, no FIND action is needed. Simply: SEND EmailNotificationName to SystemSettings
You could also send an email to a RegularUser with LoginName of admin by:
FIND RegularUser WHERE RegularUser.LoginName='admin'
SEND EmailNotificationName TO RegularUser
It is no different than sending an email notification to any other user. First you have to put the user into context, then send the email notification.