pack/compress netcdf data ("add offset" and "scale factor") with CDO, NCO or similar - netcdf

Question

I have heavy netCDF files with floating 64-bits precision. I would like to pack using specific values for the add_offset and scale_factor parameters (so then I could transform to short I16 precision). I have found information for unpacking with CDO operators but not for packing.
Any help? Thank you in advance!
Edit:
diego#LAcompu:~/new$ ncks -m in.nc
netcdf in {
dimensions:
bnds = 2 ;
lat = 202 ;
lon = 62 ;
time = UNLIMITED ; // (15777 currently)
variables:
float lat(lat) ;
lat:standard_name = "latitude" ;
lat:long_name = "latitude" ;
lat:units = "degrees_north" ;
lat:axis = "Y" ;
float lon(lon) ;
lon:standard_name = "longitude" ;
lon:long_name = "longitude" ;
lon:units = "degrees_east" ;
lon:axis = "X" ;
double t2m(time,lat,lon) ;
t2m:long_name = "2 metre temperature" ;
t2m:units = "Celsius" ;
t2m:_FillValue = -32767. ;
t2m:missing_value = -32767. ;
double time(time) ;
time:standard_name = "time" ;
time:long_name = "time" ;
time:bounds = "time_bnds" ;
time:units = "hours since 1900-01-01 00:00:00.0" ;
time:calendar = "gregorian" ;
time:axis = "T" ;
double time_bnds(time,bnds) ;
} // group /
diego#LAcompu:~/new$ ncap2 -v -O -s 't2m=pack_short(t2m,0.00166667,0.0);' in.nc out.nc
ncap2: WARNING pack_short(): Function has been called with more than one argument
diego#LAcompu:~/new$ ncks -m out.nc
netcdf out {
dimensions:
lat = 202 ;
lon = 62 ;
time = UNLIMITED ; // (15777 currently)
variables:
float lat(lat) ;
lat:standard_name = "latitude" ;
lat:long_name = "latitude" ;
lat:units = "degrees_north" ;
lat:axis = "Y" ;
float lon(lon) ;
lon:standard_name = "longitude" ;
lon:long_name = "longitude" ;
lon:units = "degrees_east" ;
lon:axis = "X" ;
short t2m(time,lat,lon) ;
t2m:scale_factor = -0.000784701646794361 ;
t2m:add_offset = -1.01787074416207 ;
t2m:_FillValue = -32767s ;
t2m:long_name = "2 metre temperature" ;
t2m:missing_value = -32767. ;
t2m:units = "Celsius" ;
double time(time) ;
time:standard_name = "time" ;
time:long_name = "time" ;
time:bounds = "time_bnds" ;
time:units = "hours since 1900-01-01 00:00:00.0" ;
time:calendar = "gregorian" ;
time:axis = "T" ;
} // group /

Answer 1

NCO will automatically pack with optimal values for scale_factor and add_offset with, e.g.,
ncpdq -P in.nc out.nc
and you can add lossless compression as well with
ncpdq -P -L 1 -7 in.nc out.nc
Documentation at http://nco.sf.net/nco.html#ncpdq
and ncap2 accepts specific values of scale_factor and add_offset for per-variable packing with pack() documented at http://nco.sf.net/nco.html#ncap_mth
Demonstration:
zender#spectral:~$ ncap2 -v -O -s 'rec_pck=pack(three_dmn_rec_var,-0.001,40.0);' ~/nco/data/in.nc ~/foo.nc
zender#spectral:~$ ncks -m ~/foo.nc
netcdf foo {
dimensions:
lat = 2 ;
lon = 4 ;
time = UNLIMITED ; // (10 currently)
variables:
float lat(lat) ;
lat:long_name = "Latitude (typically midpoints)" ;
lat:units = "degrees_north" ;
lat:bounds = "lat_bnd" ;
float lon(lon) ;
lon:long_name = "Longitude (typically midpoints)" ;
lon:units = "degrees_east" ;
short rec_pck(time,lat,lon) ;
rec_pck:scale_factor = -0.001f ;
rec_pck:add_offset = 40.f ;
rec_pck:_FillValue = -99s ;
rec_pck:long_name = "three dimensional record variable" ;
rec_pck:units = "watt meter-2" ;
double time(time) ;
time:long_name = "time" ;
time:units = "days since 1964-03-12 12:09:00 -9:00" ;
time:calendar = "gregorian" ;
time:bounds = "time_bnds" ;
time:climatology = "climatology_bounds" ;
} // group /

Answer 2

So this was simpler than I thought in cdo
cdo pack in.nc out.nc
This packs with optimal add_offset and scale_factor, converting the field to I16.