“Thusly” can be used in a humorous context, but if you do it, put up a sign. Otherwise, chances are nobody will get it; they’ll wonder why you didn’t use “thus.”
Some recent examples:
1. “President Bush should declare this nonoccupation doctrine thusly:”
2. “This week, he used that venue to renew his criticism thusly:”
3. “Last Thursday night, he introduced an immigration story thusly:”
4. “That someone is Ira Winkler, a company employee who labeled himself thusly in his 2005 book ‘Spies Like Us.”’
Some of these seem to be going for humor; in our book, only the last one makes the bar.
If tempted by “thusly,” and the unusually constructed (no “ly”) but highly standard adverb “thus” seems odd, see if “this way” (or “that way,” as in “labeled himself that way”) will work. Bet it will.
Send tips and ideas to firstname.lastname@example.org.