In general, South America is not well set up for travelers with disabilities, but the more modernized Southern Cone countries are slightly more accommodating – notably Chile, Argentina and the bigger cities of Brazil. Unfortunately, cheap local lodgings probably won't be well equipped to deal with physically challenged travelers; air travel will be more feasible than local buses (although this isn't impossible); and well-developed tourist attractions will be more accessible than off-the-beaten-track destinations. Start your research here:
Access-able Travel Source (www.access-able.com) Offers little information specifically on South America, but provides some good general travel advice.
Emerging Horizons (www.emerginghorizons.com) Features well-written articles and regular columns full of handy advice.
Mobility International (www.miusa.org) This US-based outfit advises travelers with disabilities and runs educational-exchange programs – a good way to visit South America.
Royal Association for Disability and Rehabilitation (www.disabilityrightsuk.org) Good resource for travelers from the UK.
Society for Accessible Travel & Hospitality (www.sath.org) Good, general travel information; based in the USA.