InsightII, Homology -- how do I insert residue?

[Benjamin Z. Goldsteen]

Hello,
     I am trying to use Homology to overlay a protein sequence on the
backbone of a structure for which I have coordinates.  I think I have
figured out most of the process except for calculating the coordinates
for a residue which is being inserted.
     I am using Biosym 2.3.5 on an SGI.

Thanks!
-- 
Benjamin Z. Goldsteen