I prepared a sample project for you and I hope it can serve as a base for your requirements. Basically I bound the Text of the RadMaskedTextInput to string property (TextValue) from the ViewModel. When the TextValue changes I update the Weeks, Hours, MInutes with parsing functions. If you need also two-way binding, you will need to bind the Value property of the MaskedTextInput to some other string property from the ViewModel. This property can be basically a product of concatenation ( this.Weeks +"w"+ this.Hours + "h +...).
Let us know if this helps you move forward.
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