Custom Coding VideoWhisper Chat / elgg

I need someone to make some small changes to my website. My site is using VideoWhisper and elgg so that people can create their own chat rooms. My problems that need fixing are the following.. 1, Only members who are in the chat rooms count as an online member on the Most Active Chat Rooms list. I need this to be changed so that guests and non members count as people in the chat rooms. 2, Guests are currently assigned a username. I want guests to be able to enter any chat room using a selected username and if a member already has the username, the guest will receive a message "Sorry username already taken". Basically, the database needs to be checked when a member uses a guest username, if its taken, they can not use that username. This is a small project and I am looking for someone asap to fix these issues. I will be wanting more work done after this first task, so it could be a permanent job. I need this done asap as the last person let me down having suddenly gone ill after a week!