This plugin adds a new locator node to maya- "cameraFrustum" and a new undoable command - "createCameraFrustum"
- place "cameraFrustumPlugin.py" in your MAYA_PLUG_IN_PATH folder
- select a perspective camera that you wish to add a frustum to
- run "createCameraFrustum" in MEL ( "import maya.cmds as cmds; cmds.createCameraFrustum" - python)