I've been running play by post forums for Pathfinder for about three years now. I also searched for alias functionality for awhile but was unable to discover anything, so I set about taking the initiative to get this functionality to my forums by any means necessary. I hired a programmer to begin making modifications to my site for numerous things, alias "Post-As" functionality, Custom user variables for each player (Hit Points, AC, Spells, Abilities, etc.). The work was completed about 80% and he abandoned the project. Frustrated I had invested hundreds of dollars without a finished product, I took it up myself to complete it and eventually had it functional for 3.0.
Fast-forward to about a month ago I started the process to migrate my site to 3.1, but struggled mightily as I had so much custom work on the code that was not a simple module I could remove or transfer. I've transferred much of the functionality now, though I still have numerous things that don't work correctly.
This is what it looks like currently for posting. All of this is enclosed in a tab that is not displayed by default, the post body is below the collapsible div of Gear at the bottom.
Basically what I do is have a user register a new account for each alias they want. Once they have done so, they never need to log in to that account again and only need to use their primary account. I a table called subaccount which holds the user_id of the primary account and the user_id of the alias accounts. When you load the page a query runs to find the following:
1)Find all subaccounts for the user_id of your primary account
2)On the backend I create a group for each forum and set that alias account as a primary member to that group. So then I select which of the subaccounts has a default primary membership to the forum you are posting in and pick that account from the dropdown box. This way when you post in a forum, it should automatically pick the correct subaccount each time, but allow you to change it if you wish.
Below the post-as is a bunch of custom fields I've designed. There are more then what I have displayed here, the layout is mostly about functionality right now - I haven't prettied it up too much yet, but you get hte idea.
When
viewing a topic, you can see they are viewed as separate accounts, even though they are both linked to me.
I am not what I consider a skilled programmer, I get by through a lot of trial and error and google-fu. I wish I were skilled enough to package this up for everyone to share, but I am not. It is deeply hardcoded into much of my site, and I would consider it insecure and still in alpha with several errors out there.