recoding a buffer coding system

[Santiago Mejia]

I am trying to make a script that downloads a webpage and reformats it
into enriched-mode.

I have managed to successfully reformat the raw html tags into
enriched-mode tags.  However, when I try to display the buffer in
enriched-mode (by using (format-decode-buffer 'text/enriched)), some of
the non-ASCII characters get screwed up (German umlauts, to be precise).  

I have managed to solve the issue through a nasty trick: saving the
file, killing the buffer, and reopening the file.  But this is a trick
that I would like to avoid.  

Any ideas as to how to do it?

Santiago.