From the pool lane in California can you cross over when you have a white line and next to it is two yellow lines to get to the outside lane?
Can't answer for California, but in New York the answer is no - you may not cross a double solid line to enter or exit a car pool (HOV) lane. I suspect the answer is the same for California.
Entering and exiting the carpool lane on the freeway is regulated by the type of line on the right hand side of the lane. The driver can enter or exit the lane only when the lane is not bordered by a white solid line.
Deceleration lane AKA, Ramp
A weave lane is the part of the highway or freeway where both an entrance and exit exist. It is called this because cars will be weaving in and out of lanes to either enter or exit.
Do Not Cross/ Stay in your lane Do Not cross double lanes to pass another vehicle
maintain a safe cushion of space ahead and behind your vehicle
SAFELY merge into and through the slower lanes of traffic. If you cannot do so before your exit is reached, continue on the next exit by driving in Lane 4 - exit there and then return one exit to your original destination.
The number one lane
A carpool lane is a special freeway lane only for buses and/or carpools. You may use a carpool lane or onramp if your vehicle carries the minimum number of people required for the carpool lane or you drive a low-emission vehicle displaying a special DMV-issued decal. Motorcycle riders may use designated carpool lanes, unless otherwise posted. Signs at the onramp or along the freeway tell you the minimum number of people required for the carpool and the hours the carpool requirement applies. The pavement in this lane is marked with a diamond symbol (◊) and the words "Carpool Lane." These lanes are also known as high-occupancy vehicle (HOV) lanes. Do not cross over double parallel solid lines to enter or exit any carpool lane except at designated entry or exit places. Vehicles towing trailers are typically not allowed to use carpool lanes because they must drive more slowly and are usually restricted to the right-hand lane.
You're supposed to have exited the lane well before the white line turns solid. You're not supposed to cross over a solid line - either white or yellow - for any reason, emergencies notwithstanding.
Depending on which country you are in. Generally it means 'Do not cross', keep to your your lane, no passing.