Sample code:
GeoprocessingParameters parameters = new GeoprocessingParameters(GeoprocessingExecutionType.AsynchronousSubmit);
parameters.Inputs.Add("xMin", new GeoprocessingDouble(XMin)); // #0
parameters.Inputs.Add("yMin", new GeoprocessingDouble(YMin)); // #1
parameters.Inputs.Add("xMax", new GeoprocessingDouble(XMax)); // #2
parameters.Inputs.Add("yMax", new GeoprocessingDouble(YMax)); // #3
etc
Output viewed in Fiddler:
Include_Attributes=false&Layout=S_Portrait_8x11&LineGraphics=&Map_Scale=6000&Map_Title=test2&PointGraphics=&PolyGraphics=&Spatial_Reference=2276&TimeStart=&Visiblelayers=&env%3AoutSR=%7B%22wkid%22%3A102100%2C%22latestWkid%22%3A3857%7D&f=json&returnM=false&returnZ=false&xMax=2480009&xMin=2476167&yMax=7106436&yMin=7103763