Access Read-Only Properties of Class (GeneralizedLinearModel)

I want to edit the property of a class. For example:

X=randn(100,1);
Y=X + randn(100,1)  
mdl=fitglm(X,Y)

but apparently the properties are read-only

>> mdl.Coefficients.Estimate(2)=2
Error using classreg.regr.CompactFitObject/subsasgn (line 233)
The Coefficients property for class GeneralizedLinearModel is read-only.

Is this possible?