you know, i bet someone on the DIY tribe would know. have you tried posting there? do-it-yourself.tribe.net

i had to do this earlier this year, imported a bunch of entries from a hand-coded journal site i kept 2001-2003. i really can't remember specifically what i did, i kinda monkey-wrenched it and eventually figured it out, but the basic jist:

your wordpress database is mysql. your database can output as mysql, but also as a csv file, which translates to excel and basic text. if you have a pre-existing wordpress site, export your database as mysql (see wordpress.org, i think the "how to backup your database" is linked off the download page), and open it up in a text application, so you can see what it looks like. if you are extremely anal-retentive, you could, theoretically, using word, condense all of your entries into one document and format so that it'd be acceptable as a mysql import. i did, honestly, do this, but i can't tell you how i did it, or if how much time it took to format the import document was worth it.

i know this doesn't necessarily help you, but it does show you one possible way to look at it. there may be much more efficient and brilliant ways to do this.

a caveat: if you are going to play around with your database, do it with a dummy. or, backup your real one, make sure it's safely recorded somewhere, then play.