Hi,
I am not sure I follow the question.
You seemed to have linked to one of my replies on the first page and I can't see where I mention anything about any account.
Basically you have any Apple ID.
You can add it to an iPhone (in addition to the number) and it will be linked to the Number and you can then chose the Send From choice from the Receive At options (number and Apple ID)
This is done in Settings > Messages after your Enable the Messages app.
On the Mac you can use an Apple ID to "register" for iMessages.
If you have never used Messages on the Mac before it is the first thing it asks you.
If not open th Preferences from the Messages Menu in the Menu bar and then open the Accounts pane.
You add the Apple ID here.
It may ask you to answer an email to verify the Apple ID.
You start here and the Manage option to check if your Apple ID is verified.
Mine looks like this on that ID page
As you can see I managed to add a Second email and Verify that as the Primary Email and further down I added the original email and verified that.
This was because I linked the Apple ID to iCloud and also because it is a dial-up service email that I was hoping to drop but have not been able to.
As a consequence of that the page now want me to choose one but then only offers me the Original Apple ID in the drop down.
8:01 pm Friday; January 3, 2014
iMac 2.5Ghz 5i 2011 (Mavericks 10.9)
G4/1GhzDual MDD (Leopard 10.5.8)
MacBookPro 2Gb (Snow Leopard 10.6.8)
Mac OS X (10.6.8),
Couple of iPhones and an iPad