I'm looking for sitemap software that can, for example, get the priority and frequency from a tag placed on the page. I have a site where I could easily add calculated data to each page as desired but it's not reasonable/possible for me to change the priority en mass as typical software does so I need something with more control. Also, the URLs don't have any uniqueness that would allow my to make changes using RegEx, etc so currently every page must be changed individually.
I know there's a lot of speculation about priorities and frequencies but the software that I use now has an algorithm to determine the priority. Although I can't see an exact correlation between the priority and the crawl, it seems clear that there is a relationship. I assume Google uses a combination of time dedicated to your site, traffic, priority and frequency/last mod dates. I guess that only The Great Google Machine knows for sure.
Another idea is that I could use an XML editor that has a REgEx find-and-replace. Any ideas along those lines would be appreciated.