We don not support cpyth-1.X and cpyth-2.X interfaces anymore. If you would like to pass you CompHEP events through PYTHIA/HERWIG, download and install CompHEP-4.5 and pass your sample through traslator ar first. You will receive a new sample in the LHE format (hep-ph/0609017). LHE is supported by PYTHIA by default and HERWIG (with a simple code in CompHEP-interfaces-3.00 or later).
CompHEP-interface-3.0.0 provides a simple environment for working with events in LHE as external event flow in PYTHIA and HERWIG.
If you really need an old interface (cpyth-1.X/cpyth-2.X), contact us directly.