Jim, you can manually edit saved web presets from within the Lightroom/Web Templates folder that sits alongside Web Galleries.
The top of the file looks like this:
internalName = "Panic - Shadows",
title = "Panic",
type = "Web",
value = {
AgWPGTemplateVersion = 1,
properties = {
templateId = "net.theturninggate.web.Panic",
},
internalName is the name of the preset; templateId is the unique identifier for each template, found at the head of the galleryInfo.lrweb file. This is how the preset identifies which template it should be associated with.
Following this, there's a load of gibberish, which I believe is the data for the preview image for the preset, then, at the bottom of the file, are the actually settings that have been changed from default.
That's important -- CHANGED FROM DEFAULT. That should meant that if you leave unshared, template specific options in a template at default settings, those settings should not be recorded in the preset file. That preset could then, theoretically, be applied to any other template with identical settings.
I haven't tested this thoroughly, but I have duplicated and manually edited presets to apply them to new development versions of my galleries.
For example, if you create a header setup for a TTG gallery and want to apply the same settings to another TTG gallery that employs the same header ...
So, you'd open a new template, setup the header, then save a preset. Quit Lightroom. Duplicate the preset and edit the copy. Give it a new internalName and templateId (get the templateId from the galleryInfo.lrweb file of the template you want to apply the new preset to).
Launch Lightroom, and access the preset. It should load the new gallery with your settings.
Like I said, I haven't tested this thoroughly, but I've used the idea before between two development builds of the same gallery template, and I see no reason it shouldn't work for galleries with identical settings, such as the header options in most of the HTML-based TTG galleries.
Cheers,
Matt