how can I tell emacs to treat a text file as html?

[Angelina Carlton <brat@magma.ca>]

Hello

I use a bash based blogging software called nanoblogger. It lets you
use the editor of your choice and I had set this to be emacsclient.

The blog script then sends /tmp/nb_entry1078.html to my already
running emacs and I can edit using html syntax hilighting as emacs
recognizes the file type.

This worked fine until the latest version of the software now sends
a txt file instead. /tmp/nb_entry1078.txt  

Emacs of course thinks this is plain text which is right, but I would
like to treat it as html, actually XHTML, but either would do. 

The blog conf file has:
EDITOR="emacslient";

I cant find in my documentation a way to set EDITOR to 
"emacsclient --"treat this as html"

Is this possible from the command line? Or is there a way to turn on
html font locking from inside emacs even if the file is txt? This
would be acceptable if I could bind it to like F8 or something.

Thanks in advance..  
-- 
Angelina Carlton