The MCSCF/CASSCF hessian can be computed analytically (only without symmetry) using
CPMCSCF,HESS,[ACCU=value]
where the ACCU option specifies the convergence threshold in the CPMCSCF calculation (default 1.d-4). The hessian is stored on record 5300.2 and can be used in a subsequent frequency calculation.
Example:
{multi;cpmcscf,hess,accu=1.d-5}
frequencies
Note that the NOEXTRA option is used when computing a hessian.