Heat oven to 300°F. In large bowl, mix cereals; set aside.
In 1-quart saucepan, heat butter, chili powder, garlic powder and cumin over medium heat, stirring occasionally, until butter is melted. Pour over cereal mixture in bowl, stirring until evenly coated. Immediately sprinkle with cheese, stirring until evenly coated. Spread mixture in ungreased large roasting pan.
Bake 30 minutes, stirring every 10 minutes. Cool completely, about 15 minutes. Store in airtight container.