Yes, i think so. You can either create several nodes in .gmfmap model and
constraint them to be applicable only if this attribute is set to some particular
value(s), or modify ???EditPart.setupContentPane() method to pass proper
EditPart to the newly created node figure (you can use CustomFigure for it).
Then you have to add domain model listener listening for the changes in specified
attribute and performing refresh (parent node update/surrent node figure
repaint) then attribute value was changed.