Help with importing categories

Hi,
I have several static pages going back 13 years that we are converting to WP. We want to create a hierarchal category structure that has some sub-categories of the same name. For example, articles in category coffee will exist in a parent category July. July is a subcategory of 2012 and other years. This will be repeated in all 12 years of content like so:

2012/July/coffee
2011/July/coffee
2010/July/coffee

… etc.
Same is obviously true for other months and even other sub-categories like coffee (example: sugar, wheat, etc). So we will have a lot of category structures like this:

2012/July/sugar
2005/May/wheat

… etc.

I don’t understand the Categories, Tags, Taxonomies section documented here: http://stephanieleary.com/downloads/html-import/user-guide.html#getting-help
How do I format my incoming static HTML to pick up category hierarchy? In the HTML Import Plugin settings, there is this statement:

To import tags from a region in each file, use a custom field with the name post_tag.

Does that mean I do something like this?
<div name="post_tag">2005>May>Wheat</div>

Any help you can provide would be greatly appreciated. Thanks for making this plugin available, by the way. It’s awesome.
-Keith

http://wordpress.org/extend/plugins/import-html-pages/