Sorry I missed this and didn't reply earlier.
If using Instant TV Channel, there is an option to use MRSS (XML) files to specify some or all of the channel's content. Basically you provide Instant TV Channel with one or more URLs pointing to your MRSS files. Multiple MRSS formats are supported. Here is some additional information:
http://www.InstantTvChannel.com/roku/mrssIf not using Instant TV Channel, many channel designs, like the ones based on Roku's SDK examples, will use XML files to determine all of the content of the channel. I'm not sure if this is what you were asking, but what you usually need to do to change the content of a channel is to edit one of the channel's XML file on your Linux server, or wherever else you have the XML files hosted like Amazon S3 or CloudFront. You'll probably need to use more than wget or curl to do that.
Scott
Instant TV Channel
