We have formulated composites of lead (II) tetrakis (4-cumylphenoxy) phthalocyanine (PbTCPc) doped into nematic liquid crystal (LC), $4^{\prime }$ -pentyl-4-biphenylcarbonitrile (5-CB), that has received a $90°$ twisted alignment and investigated the nonlinear transmission properties using both pulsed (Nd:YLF $524\mathrm{nm}$ , $5\mathrm{ns}$ ) and cw ( $532\mathrm{nm}$ ) lasers. In the nanosecond regime, this compound is a reverse saturable absorber performing similarly to low-concentration solutions of PbTCPc. Under cw conditions, we observe optically self-activated polarization switching with low threshold input energy. Our results suggest the potential for an all-optical switch working from the nanosecond time scale to cw.