While popular culture often depicts Native Americans as technologically backward hunter-gatherers, the reality was far more complex. Numerous groups understood the advantages of the advanced technology being brought in by foreigners, and they adopted it where it proved useful. Often this involved weapons technology, but this could also encompass civilian tools and materials. In a steampunk context, this means that there is no reason that a Native American group or individual could not have access to the same advanced technology as a European; and given the interrelation between steampunk and historical speculation, there is no reason why a steampunk setting could not rewrite its background to allow sedentary Native Americans access to industrialization. In this same way, the groups that had already been colonized by the turn of the 19th century could easily be re-imagined in an industrial age context, either having retained their cultural distinctiveness in spite of colonization or having repelled the arriving Europeans outright. There is nothing that says you cannot have a 19th century steampunk Aztec, provided you are willing to explore how their empire survived into the 19th century and why they industrialized.
Finding a starting point for approaching "Native American steampunk" can be difficult for this very reason: the simple diversity of peoples and cultures that fit under that title. Many Native Americans groups had already been invaded, subdued and colonized by the time the steam age arrived (specifically, the best known civilizations of Mesoamerica and South America--the Aztecs, the Maya and the Inca--but also many of the peoples residing in North America's eastern regions), but still others retained their independence by the dawning of the 19th century (the various tribes in the "American West" are the most famous, but there were others such as the Seminole in the Florida region). Some Native Americans were nomadic, some sedentary; some were hunter-gatherers, while others were farmers or herders. Cultures, belief systems, languages, social systems and clothing styles all varied tremendously. Moreover, many Native American cultures represented highly organized unions, confederations or alliances between various groups (for example, the Iroquois were composed of several distinct groups bound together in a league of nations); the Native Americans also had their own expansionist empires, of which the Aztecs are the most famous.
The sheer diversity present among the Native Americans means that it is often easier to choose a region or group to focus on for a starting point, rather than tying to examine the Native Americans as a whole. Above all have fun with this, but be prepared to uncover a tremendous wealth of wonderful historical and cultural information if you begin looking into the subject of Native Americans and their potential place in a steampunk setting.
-G. D. Falksen
Warriors on horseback
A group of Chippewa; note the mixture of European and Chippewa clothing
A group of Iroquois from 1914 (part of a much larger panoramic photograph)
Coeehajo, a Seminole chief
A Comanche chief
Opothleyahola, a Creek chief