Monterroso, who had a pair of goals in Los Chapines' 3-1 win over Costa Rica on Tuesday, gave Guatemala the lead in the 27th minute and then added an insurance goal in the 72nd.
Gabriel Mejia also scored in the 35th minute to put Guatemala ahead 2-0 before Jenny Hernandez tallied in the 56th to pull Honduras within a goal.
The two wins finished Guatemala atop Central American Group 1 with six points, three better than Costa Rica and pointless host Honduras.
Guatemala, which played in its first finals as host of the CONCACAF U-20 Women's Championship in 2010, joined automatic qualifiers Canada, Mexico and the United States in the eight-team field.
Central American Group 2 will begin play Wednesday in Panama with the host, Nicaragua and El Salvador, again with the winner qualifying for the finals.