To use a custom portrait you need to sellect it at character creation, otherwise it takes filing a request in the Disputes/Grievances section of the forum and requires a DM to make the change if it's done after the character's already been created. If you do have to file such a request, make sure to supply the custom portrait files, or links to where the DM's can get them in your request. Also needed will be your exact character name for the character and your exact bioware name for yourself.
Further, no one else will be able to see your custom portrait in-game until after it has been included in the updated Layonara portrait pack, or if you get them the portrait files on an individual basis yourself somehow (i.e. - providing the links to where the files can be downloaded or emailing them directly to your friends).
For folks who are making their own custom portraits, more information is available at:
http://nwn.bioware.com/builders/portraits.htmlKeep in mind if you're not the original artist of the image you intend to use that you should acquire permission from said artist in order to avoid causing problems regarding copyright infringement.
