If the pages are important, then you should add them to the site map so they can be indexed for future reference. However, if the pages are going to disappear after the match, then I wouldn't put them on the site map as they may get indexed then disappear, which may have a negative impact on your search engine rankings.
You can add these dynamic pages to a site map in a couple of ways:
Whenever a new dynamic page is created, re-create your site map. Do this by looking through the database for the pages which will be valid and writing them out into an XML site map file.
When a new page is created, read the current XML site map, and insert a new entry into the relevant place.
I would say the easiest option is option 1 as you can quickly and easily build a site map without having to read what you already have. That option also means that when you remove a one of the dynamic pages, it will be removed from the site map when it is re-built without the need to read through what you have, find the entry and remove it.
Google code has a number of different options for you, some of which you can download and run, others look like they need implementing within your own code.