I don't use the To Go portion of Docs to Go, but you may be able to open your memo, Select All/Copy, then create a new Word to Go document, then paste the copied memo, then save to card.
Alternately, if you have HotSynced (so the memos are in Palm Desktop), you can do the same thing. If you have a card reader connected to your computer, you could even save as a native Word .doc file, then save to /Documents on the card.