I teach comics and graphic novels and while I've never used theories of multimodal literacy to do so, I can see very much how they apply (and have read scholarship advocating for it).

Comics use a combination of visual and textual (literary) content to make their meaning and can only do so through their relationship to each other. The visuality of the comics medium informs how the text should be read and vice versa. This is particularly powerful when the two are sending conflicting messages, which in their combination produce a third meaning or narrative. The color, composition and layout all inform the reading experience as much as the changes in font and layout of dialog. The way an image is produced incorporates emotional responses in the reader, while the layout of the dialog or narrative might guide different reads through the story differently.

I also think it's interesting to consider the tactile quality of comics reading in either their tradition book or floppy format or through digital means and how this produces different kinds of engagement with the texts. Some comics need to be flipped around to follow the text, so the book itself becomes essential in the reading process.

Ultimately, comics reading is highly interactive process that highlights the agency of the reader through the mobilization of many kinds of literacy. The meaning of the narratives themselves thereby becomes very subjective, since it is dependent upon the kind of experiences readers bring to reading comics.