Thank you for your feedback. JustCode "Create Property" command does not support the scenario you described. However, you can write an extension for JustCode which does this. I created a working extension following your description and I am attaching the solution.
You can modify it further if you want - for example change/remove the shortcut, the text that will be shown and the identifier. This command can be executed on a field and will create a property which have "OnChange" in its setter.
You can go even further and make it to check whether the new value is different than the old one and call OnChange only then.
In order to get this extension working you have to build the solution, then copy the dll and pdb file, go to (Program Files)/Telerik/JustCode/Libraries and create "UserExtensions" folder. Finally, paste the dll and the pdb in this folder and start a new instance of Visual Studio.
If you want to debug the extension just start debugging in the solution I am sending you.
If you have any questions regarding JustCode and its API, please do not hesitate to contact us again!
the Telerik team