Hi,
iChat used to do this differently.
The so called Smiley was actually sent as the text.
The app then "saw" it in the incoming stream and changed it to the pic.
So your end sort of "posted" the pic if you sent a Smiley and the other end interpreted it as a Smiley and added one to the incoming side/balloon.
This caused all sort of issues when people added Smiley packs to early versions such as iChat 2 and 3
(it was how Ryan M. discovered the Reinstall method).
It did seem that later versions did actually send a smiley pic for the text you typed in.
As all version up to Message 7 also had the menu item to either Show Smilies or Hide them it is a little difficult to say with any certainty how that was achieved.
As Messages 8 does not have an option for Showing or Hiding Smilies you cannot find an old chat with a Smiley and turn it On and Off to find out what happens.
I am not sure how the AIM for Mac app or the PC version works in this respect.
I would guess the Emoji is sent as a pic.
If not it will then be a two character substitution which cannot be interpreted by the AIM app itself.
I sent a Smiley from one Account I have to another.
I cannot "drag" the Smiley the way I can a Picture that has been sent.
If I highlight it and copy it and paste it in TextEdit it remains an Emoji icon.
Even trying to change the Font to see if it will display as ":)" does not work - you cannot change it from Emoji.
I am not sure there is gong to be a work around.

8:38 pm Friday; April 25, 2014
iMac 2.5Ghz i5 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