In my opinion it is still a piece of work equipment and so would fall under PUWER and more specifically LOLER. I honestly do not think that if you are using it to lift a load with a crane that it cannot be considered a lifting accessory and therefore should be subject to thorough examination every 6 months. Perhaps I am wrong but this is how i would see it.

I hate to disagree with Ron but technically even supply to oneself attracts the Supply of Machinery Safety Regs (see Reg 2 definition of manufacturer). But wait - if your engineers have done a proper design job, with reference to relevant harmonised standards (or advice from the likes of your LOLER Competent Person), then they have virtually got you there already anyway. Chat to your CP about the support they can give you. You (thankfully!) don't need to worry about EMC in this case. Assuming you aren't doing a lash-up because you've asked this question, then don't run away from the certification issue. It's not as bad as it sounds if you involve the likes of your LOLER CP asap.