An R file (R is available from http://www.R-project.org for the model for the paper

A circuit model of the temporal pattern generator of Caenorhabditis egg-laying behavior
Zhang M, Schafer WR, Breitling R
BMC Systems Biology 2010, 4:81 (7 June 2010)

is available from this link provided in the supplemental material:
http://www.biomedcentral.com/imedia/1815250998377258/supp2.r