if you only have the Valet, you will need a new ECU or the old one fleashed (flashing is not easy to comeby, you'll have to speak to loads of locksmiths, cost's, apaarently, £500) A new ECU is £2000 from Lexus! you will not need a new barrels or locks because a master key blade can be cut from a vallet key. The valet profile is different but the cut channel in the centre is the same for master and valet, what stops the valet key working in the dash and boot barel is because its about 2mm narrower, here's a diagram looking at the end, valet on left, master on right
The master Key has remote boot opening and alows the car to have a new key (master and Valet) programed for the car.