HELP: sites to raster - attributes

[Jay]

We are using grass4.1 trying to convert sites files to raster files. 
Using s.menu we are able to convert the sites into a raster map displaying
either a 0 or 1 (1 for a site occuring in that cell).  

Our sites files contain an attribute which is snow depth.  We want to
convert the sites file into a raster file, where the raster value is
the snow depth of the site in that cell (or average of sites in that cell
if there are more than one).  Basically we can't figure it out.

We are using s.menu with option 7 to create a frequency based raster file,
but we aren't sure how the categories are determined.  Can we define our
own categories?  

As a side note, can d.colors take an input file instead of needing a 
user to go in for each raster file and manually switch RGB values?  

Thanks for any help..

Jay Wright
Marilyn Hughes
Rutgers Geography