Это можно сделать с помощью класса окна:
См. Код ниже для демонстрации
MyWindowType myReport = new MyWindowType(); // create a window, MyWindow is an User Control of type Window, that is it extends Window
MyCrystalReport myReport = new MyCrystalReport();
// Do necessary modifications to myReport such as Add Data and Send Parameters
CrystalReportViewer rptViewer = new CrystalReportViewer(); // Construct a ReportViewer
WindowsFormsHost host = new WindowsFormsHost(); // Create a WindowsFormsHost
rptViewer.ReportSource = myReport; // Add Report to ReportSource
host.Child = rptViewer; // Add report viewer as child to host
myReport.reportGrid.Children.Add(host); // Add host to MainWindow, that is myReport in this example
myReport.BringIntoView();
myReport.Show();