Howdy,
 
Well, here is the stuff that I found:
 
The first pics 2 in the thread are of the "Enlarge Person" spell.
The other 2 pics are of a character edited in the editor.  
 
You can edit the size of any character in the editor by bringing up it's properties and adjusting its scale value.  You can also create blueprints of already scaled characters for spawn events or easier placement. 
 
You can adjust a character's scale dynamically in custom modules using scripting.  I attached the following script to a character's conversation so that if a specific option is selected, the character the player is talking to will double in size for 20 seconds:
----------------------------------
void main()
{
 object oMonster=OBJECT_SELF;
 
 effect eGrowth=EffectSetScale(2.0);
 ApplyEffectToObject(DURATION_TYPE_TEMPORARY, eGrowth, oMonster, 20.0f); 
}
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Also, it's good to note that this function is based off of a character's current scale, not it's default scale.  So running this routine multiple times will make for a very large character.
 
Lastly, there is a way to edit your save and character files to adjust scale:
There is a data file editor that allows you to change information on just about any character file. 

You can get the editor here: 
http://nwvault.ign.com/View.php?view=other.Detail&id=247 

Then, you need to open up your save file folder and look for the corresponding character. I used the playerlist.ifo for my character and the ROS-{companion name}.ros file for modifying companions. Among the many listed things there is ... model scale. Save the file and load your save game and viola! 
 
Just an note, the editor and scripting methods are for custom modules only.  I wouldn't recommend editing the campaign files that come with the game.
 
Regards,
-DAllen