In reply to samrihughes:
Have you tried getting in touch with the Asociacion de Guias de Montana del Peru (Mountain Guide Association of Peru)? Admittedly, the office/info centre/meeting point (Casa de Guias) generally looked closed when I was there, but they have a list of all members so would be a good start.
Casa de Guias
Parque Ginebra 28G
Huaraz
tel. (+51)43 42 1811
email informes@casadeguias.com.pe
www.casadeguias.com.pe
There's a noticeboard that you can put a note on to look for partners too.
Try emailing or phoning Galaxia instead.
galaxia_peru@hotmail.com
(+51)43 42 5355
I have a few other random contacts in the town who may be interested in helping/organising something for you. Email me if you'd like some more info.