Ah. Too bad, that was the easy way ;) lol
This seems like it has what you want. http://www.tomauger.com/2011/tips-and-tricks/mysqldump-one-liner-to-export-wordpress-tables-in-a-shared-database
MySQL apparently does not support wildcard selectors (news to me, though I haven't done anything command-line in mySQL in a while) but this solution is a cute workaround. It combines the "export all explicitly specified tables" command with "replace the explicit table names with a sql query that gets me only the table names I want by querying the schema directly".
I hope it works for you!