2004 Ascender Keyless Entry

I am looking for some help with the keyless entry on the vehicle I
just purchased.

Last month I bought a 2004 Isuzu Ascender that is equipped with
keyless entry. The issue was that there were no remotes for the
vehicle. The dealer gave me a different remote that can be programmed
to work with the Ascender, and told me to check with the garage to
have it programmed. Well when I did they told me there would be a 3 to
4 week wait and a charge of $100. Now I have heard that it is possible
to program the remote to work yourself. However despite all my
searching I am unable to locate any information on doing so for this
year/make Isuzu. If anyone out there has instructions for going about
doing this, I would be greatly appreciative if you could email them or
post them for me.

Thanks