technically, you can:
http://forum.techinferno.com/diy-e-gpu-projects/2109-diy-egpu-experiences-%5Bversion-2-0%5D.html
i doubt that Lenovo comes with an Express Card Slot, so you're left taking the mPCIe route. in the off chance that Lenovo has a Thunderbolt port, that as well.
there's a whole lot of caveats though; if you only have one mPCIe slot, you're left without a wireless connection if you decide to remove the wifi card for the eGPU, PROVIDED it's not whitelisted. you're also gonna have to expect to see massive drops in GPU performance compared to what it can do on a desktop; a GTX760 will likely only perform as good as a GTX640 or 650. & then there's the cabling; with several cables from the PSU & eGPU kit, it's not gonna look...