How to select Boundaries by coordinates/boxes WHILE building the geometry in Matlab?

Hello,

I am trying to automate my COMSOL model via the LiveLink interface and I am struggling at the geometry part, where I need to transform all my boundaries into "solid".

I tried the following:
index=mphselectbox(model,'geom1',['-wd' 'wd';'-wd' 'wd'],'boundary');
model.geom('geom1').feature.create('csol1', 'ConvertToSolid');
model.geom('geom1').feature('csol1').selection('input').set({index});

This gives me:
"No method 'set' with matching signature found for class 'com.comsol.model.impl.GeomObjectSelectionImpl'.

Error in Salient_Pole_20130906 (line 229)
model.geom('geom1').feature('csol1').selection('input').set({index});"

So I was hoping to be able to select all boundaries inside the "wd" square to transform them into solid. Since there are pretty many boundaries, this would save me a lot of work. But I think that the selection functions via Box or ball do not work for the geometry-creating.

Any tips?

Thanks in advance!