Writing readonly nodes from OpcUa server

[geist3]

Hi

I have some nodes that are readonly for opcua clients. I want the server to update one of these nodes in a function it has.
Is the correct way to 1) set it to writable, call baseVariableState.WriteAttribute, then set to readonly again? Or to set with baseVariableState.Value = X and do UpdateChangeMasks and ClearChangeMasks? Or something else? Any problems with these approaches?

Thanks for any help
John