Hi Natalia,
Thank you for your interest in Syncfusion Products.
To disable entering values manually and to allow to enter a value only using MonthCalender is possible by overriding ProcessCmdKey event. Kindly refer to the sample provided below that illustrates this:
http://files.syncfusion.com/support/Tools.Windows/7.2.0.20/56845_1/main.htmPlease let me know if any concerns.
Regards,
Fathima