XML Feed Managment

I have created a banner display ad that needs to contain text fields where content will be changed through XML/RSS feed. Ad will run in Google Ad & Yahoo Network. I need developer to create Action Script variables so that ad can communicate with XML/RSS feed. I need to create a webpage where to enter and schedule the different XML feeds. Example

XML Feed 1:
Start: (date&time) END: (date & Time)
Text Field 1: Listen to us live tomorrow!
Text Field 2: 8pm

XML Feed 2:
Start: (date&time) END: (date & Time)
Text Field 1: Listen Live Tonight
Text Field 2: In one Hour

I understand how XML works and how to get it to communicate with ad. However scheduling the multiple xml feeds is the challenge.. Not sure if this can be done with PHP conditions in the XML file or through a cms. But I cannot enter feed changes manually, I need to be able to set them up ahead of time so they change when conditions are met.