In terms of actual possible process description, I think the Alternative Photography website already mentioned can't be beat. However, for getting some ideas and historic background, you might also wish to look at the book listed here:

PHOTOGRAPHS FROM THE 19th CENTURY:
A Process Identification Guide

by William E. Leyshon

A direct link to a full PDF version of the book can be found in the Links section of APUG here:
http://www.apug.org/portal/?id_category=93

Marco