If you wanted to do it weekly you could just steal interesting ideas/topics that come up in IRC and see what gains the most response from people and do a 20 minute podcast every week as far as mechanic discussion. You could also talk about upcoming events and what interesting thing members of the community could be up to.
If you do it live and downloadable basically you run the discussion live (with a set list of everything you want to talk about), then just announce what interesting comments would be made on IRC and talk about it. I think it would be best to be two-man, a charismatic talker/someone very into the community (For example, Miz, Lolisauce, or Chibi would be great for this) and someone very knowledgeable about the game (For example, Tonberry/Bell/Zar/Sp00ky).
You could also run weekly segments (pick a character each week to have a discussion about), and have a person interviewed to talk about that character. For example, someone from the Mage's Association to talk about Aoko one week. Maybe ask about interesting gimmicks/setups/tips about the character.
I think this project could be really fun if prepared for properly. I used to assist a friend for his DJ work and substituted for him a few times - and also ran an online radio show for a year. The most important thing I can tell you in broadcasting is just be prepared and never ever have any dead air. It's not hard as long as you have a couple talkative people together. You can go really far with a few neat sound effects and intro/ending.