Thanks to everyone for their suggestions.  The closest solution was

1. Expand dataset in P1 using SFTOOLS (keyword EXPAND)
2. Write it out in text file
  (WRITE data.hkl  format(3i5,2f16.3) col col1 col2)
3. Use program HYDENS (Bart Hazes)

It should be noted that the current version of HYDENS only works in
orthorhombic spacegroups (although there may be a workaround of
pre-calculating fractional coordinates with coordconv and then setting
the unit cell to 1x1x1).

This was the only solution that actually calculates electron density at
the atomic positions.  The rest of options were all to calculate the map
and then interpolate it to the select (x,y,z).  Several options exist
for that (in the order they were received):

1. MAPMAN (PEEK keyword) (Gerard Kleywegt, James Holton, Edward Berry)
2. CCTBX (Pavel Afonin)
3. COOT (density_at_point, probably uses clipper libs) (Paul Emsley)
4. CHIMERA ("Values at Atom Positions") (Eric Pettersen)

On Fri, 2011-04-01 at 11:16 -0400, Ed Pozharski wrote:
> I need to calculate the electron density values for a list of spatial
> locations (e.g. atom positions in a model) using an mtz-file that
> already contains map coefficients.  To write my own code may be easier
> than I think (if one can manipulate mtz columns, isn't the only problem
> left how to incorporate symmetry-related reflections?), but I would need
> an alternative at least for troubleshooting purposes. So,
>
> Does anyone know of a software tool that can calculate point electron
> density for every atom in a structure?
>
> If I would have to bring a dependency into this, the best choice for me
> would be clipper libs.
>
> Thanks in advance,
>
> Ed.
>
>

--
"Hurry up before we all come back to our senses!"
                          Julian, King of Lemurs