A co-worker showed me this trick. Select a batch of text objects that you want to turn into mtext. Important: unselect them by pressing Esc. Pull up the text2mtext command from the Express menu. You'll get a prompt that includes the SEttings option; type SE. Uncheck the box for "Combine into a single mtext object" (I had never seen this before). Back at the command prompt, type P to select the Previous selection set. Press Enter and Ta-Da! all those single text items are single mtext items. You can give them frames or background masks or whatever.