Paul,
There are a few areas to put in for HH:
Sunset Beach off of PCH next to the Malibu Kayak Shop
PCH/Warner - Next to the Firestation on Warner (just inland from PCH - at the flashing Firestation stop light) there is a public boat launch ramp. You need to pay for meter parking to launch here.
Countess and Edinger Ave- There is a park/parking lot here and you have 2 options to lanuch. One right next to the parking lot, which can be somewhat muddy at lower tides. The second is a sandy beach on the backside of the park there (Mothers Beach). Take Edinger towards Sunset Aquatic park and just before the bridge that goes over the Edinger channel (into HH), turn left on Countess. Go up a bit and you'll see the park, parking and launch areas.
Note: you cannot gain access to the open ocean thru HH in a yak. You cannot go under the PCH bridge to the ocean side of the harbor as that area is closed to non-motorized craft (PWC as well) and is patrolled by our friends in the Navy. If you enter the closed area, a friendly group of folks with big machine guns will escort you back into the harbor
Hope this helps
Ed