The Flash Manual does not cover all suppotred HTML tags and attributes supported in text boxes.
I know of the following. Please contribute more...

<p>
attributes:
ALIGN=(right,left,center)

<a>
attributes:
HREF=(url,"asfunction:[function_name,arg1,arg2,...])

<font>
attributes:
color=(#xxxxxx)
face=(arial,etc)
size=(pt size)

<b>
<i>
<u>
<br> - this one not documented in maunal