Update InitFCN with GUI

Hi,

I have a model that has a variable defined in the InitFcn. I also have a GUI that takes an input from the user. Is it possible to update the variable in the InitFcn with the new value from the GUI?

I tried this code but the set_param command replaces all my InitFcn variables instead of updating them.

LO = get(handles.textbox, 'string');
set_param('myModel','InitFcn',LO);

Anyone have any suggestions?