charset ISO-8869-1 question

I should probably already know this (but then again, ever since I signed
up to the list I have used Yahoo webmail, with its ASCII encoding :( ),
but how can I include the eth and thorn characters in email messages?[1]
I have switched the email account that I use for the list and am now
using my Netscape account and the Netscape mail client, which DOES allow
various charsets :) I use a Macintosh (OS 9.x) and a monospaced font. I
would also like to include macrons (those are the horizontal lines above
vowels, correct?) as well, but I don't know if they are included in the
aforementioned charset. This will allow me to present Oreelynna (need a
macron for the lengthened e!) in its *native* orthography.

Thanks.

[1] for Oreelynna, of course!
--
=============
James Worlton
          "Time flies like an arrow.
           Fruit flies like a banana."
                           --Unknown