DEM from points and breaklines

I have a dgn file with z values for points and breaklines
and would like to
convert the data to a GRASS raster DEM.  I assume I just
v.in.ogr and create
a 3d output for the lines and points.  What command do I
then use to convert
the vectors (both breaklines and points)to DEM raster,
v.surf.rst only
accepts one input file it believe.

Travis Kirstine
First Base Solutions Limited
Markham, ON
Canada