Ephemeris is provided to the program through a FITS file. In the case of the Crab, one set of ephemeris parameters per month is required to follow the Crab phase over periods much longer than one month. The FITS table includes one ephemeris parameter set in each row with a validity time interval (specified through MJDSTART and MJDSTOP). The program can then automatically select a valid ephemeris parameter set (in a given row) for each processed science window. You just have to make sure that the validity intervals encompass the time span of all data included in the analyzed observation group.
We are aware that using a FITS file may be inconvenient for most X-ray pulsars for which only one set of ephemeris parameters is needed. For the time being, this set has to be provided through a FITS table with a unique row with a very wide validity interval covering the whole INTEGRAL mission.
Ephemeris files for the Crab, V0332+53, and 1A0535+262 are available at:
http://www.isdc.unige.ch/integral/download/spi/pulsar_ephemeris/Crab_ephemeris.fits
http://www.isdc.unige.ch/integral/download/spi/pulsar_ephemeris/3A0535+262_ephemeris.fits
http://www.isdc.unige.ch/integral/download/spi/pulsar_ephemeris/V0332+53_ephemeris.fits.
The meaning of the ephemeris parameters are standard, and the required information can easily be found trough the WWW. For the Crab in particular, you can look at
http://www.jb.man.ac.uk/ pulsar/crab.html
For other not so fast pulsars, some of the parameters such as second derivative can be set to zero.