PropsGuild has since become a subscription site, and most of its content is available to members only. Check the preview section, and you'll see a thumbnail image of the Scorpio Man character for Michael. It isn't the Scorpion King, but was inspired by the film.

M.C.Design has a posable scarab for sale, along with other yucky insects. You can find it here in the Marketplace; it's by mertext.

brycetech has a posable stag beetle in the Marketplace, also; it might do in a pinch.

You can download a free scarab from the archives at Baument. It's an untextured mesh in .3ds format, so it isn't posable; you'll have to import it into Poser.