Right now you can do the following to specify using a particular EPG method for a particular channel. It will require some individual tweaking of channels.
If you want to use two different online methods and use one for some channels, and the other for some other channels, you run EPG loading manually, and when the first EPG mode's XMLTVID matching window pops up, clear the ID for channels that you do not want to use that particular EPG mode. Then, when the second matching window pops up, make sure those channels are associated with the IDs of the second method.
If you need to mix OTA EPG with online EPG, clear all XMLTV IDs that you want to be handled in OTA, and use the option "In Over-the-air EPG scan (ATSC only), save programs for channels with empty XMLTV IDs only" (I should have removed the words "(ATSC only)" since we support OTA scan for DVB already).