Well, the Cadence tools only care about you having the hspice executable on your UNIX path (set using the $path variable in csh, or $PATH environment variable in sh/ksh/bash). As for the licensing, you'd set that up the same way for hspice as if you were running hspice standalone (you  could set $LM_LICENSE_FILE - or there may be a Synopsys specific variable that controls hspice licensing, I don't know).

Regards,

Andrew.