W2s?! Wow, if this isn't a typo then I'm really feeling my age for remembering them. The W2 series was an early JL Audio model. Perhaps you meant v2 series of w3 or w6?
What size are they? Specs for a proper enclosure should be available at www.jlaudio.com or you could check a local JL dealer and ask them if they have "the bible". This is a technical reference manual that has info on all models, including discontinued "classic" products.
As far as the box goes, only your imagination (and wallet) are limiting factors.
Do you have the specs or measurements or even better pictures of the installation? I'd love to do that (probably with round sups and a little bit more of an enclosure for the amp) but still I'd like to do that!