Hi CousinLarry,
I found this article on vbdesign.net... maybe it will answer your question.
http://www.vbdesign.net/expresso/archive/topic/6535.html
I've copied the code in below that Kerry B was kind enough to post.
If this works for you, let me know!
(You'll need to save this into a .lsp file, and fill in your "NewStyle" with the actual style)
(defun c:mtsc (/ nstyle index AllMtext b1 c)
(setq nstyle "NewStyle"
index 0
)
(cond ((and (setq AllMtext (ssget "X" '((0 . "MTEXT"))))
(tblsearch "STYLE" nstyle)
)
(repeat (sslength AllMtext)
(setq b1 (entget (ssname AllMtext index))
index (1+ index)
c (assoc 7 b1)
)
(entmod (subst (cons (car c) nstyle) c b1))
)
)
(t (alert "Unable to do my job today"))
)
(princ)
)
Hope this helps!
Bill