1: I wanted first to add a new custom single-line text field called "adsense".
2: In the template called "ad_message_body" I was going to put the full Google AdSense code for a 728x90 banner, but leaving the adsense "pub-xxxxxxxxxx" section empty. Replaced with the custom field code needed to grab a users value there (if they enter a pub-xxxxx number in their profile settings) for the custom adsense field section.
3: The whole adsense code was going to be wrapped in a conditional that would only show ads in the first post only (so just the thread starter got his advert displayed).
Can this be done?