Lets see if I can give some help for the people who haven't gotten it to work yet too.
Sign in with your beta tester information, choose the IM: CF3n IM server and hit the IM accounts button. It'll ask you to do guided account creation mode. Use it to create an account on CF3n IM (that'll make a Master Account on the gateway, and then take you through adding IM accounts. To change your IM accounts afterwards, hit the IM Accounts button and say No to guided account creation mode. Adding an IRC server is much simpler, just hit Server Settings on the front page.
Once you've logged into your IM gateway account, it'll pop up a list of the IM services, choose which you want, and hit connect, and it'll log you in and update your buddy list.
That's pretty much the basics. Messages from different IM services seem to appear in different tab strips at the bottom, so either remember to switch between them, or choose all.
I'm not sure what the refresh button on the buddy list page does, I'd hope it automatically updates.
Thanks for the interim guidelines, JHoff! KFU!
I don't have many chat accounts. In fact, while I use Yahoo! for a couple of email accounts, I've never chatted. Will that affect my ability to use one of them for chat? My only previous chat experience was on AOL over 10 years ago, so I'm having trouble "conceptualizing" what I'm to be doing here...