Is this any good? Would it work as a winteriser fertilizer?

Here is a link that might be useful: Miracle-Gro 1001832 Lawn Food Box, 5-Pound

The best source for fertilizers will be a "feed store". Lesco/John Deere also carries a variety or try a graden center or nursery. The chain and big box stores wont usually have what you are looking for. When reading the label, any percentage of N that is not identified as "coated" or otherwise marked as slow release is going to be fast release by default.

Ok thanks. From what I've read here, it seems like I should be looking for some 46-0-0 urea. Is this recommended?

Yes. You'll want to use that for your winterizer--sometime late October-November when topgrowth stops and you noe longer (or hardly) need to mow. You can drop any kind of N (milorganite, synthetic slow release, etc.) in a couple of weeks or so (say mid-Sept. search "Book on KBG") to keep the grass photosyntheisizing until the topgrowth stops.

Thanks for the information. And thanks for putting together the book on KBG! That will really come in handy!