modelgen and bm_

Hi,

in gnucap netlists its possible to hand bm_* expressions to elements, like
for example
gvcr out 0 vcr in 0 poly( 1, 2, 3 ).

i'm having trouble adding such devices into a .model file. for now i'm
copying code from bm_poly.cc to the "eval somevcr" section, which
doesn't seem to be the natural way.

It seems this is no implemented in modelgen. am i missing something? and
if not, what would be the recommended way to do so? any advice would be
appreciated.

thank you,
felix