Aside from the copyright / licensing legal issues ....

Games typically use proprietary formats for their geometry, and the files are often packed together.  You'd need some means to unpack the content to get at the individual files, then have an application that can read and convert those formats to something Poser-compatible.

And it isn't just the geometry.  You may well need to convert the textures and other maps, also, if they aren't merely using JPEG.

Tomb Raider is a long-lived and popular franchise, and I recall level editors, ripping tools, and various custom graphic hacks being devised for earlier titles in the series.  Your best bet is to browse through the various fansites to see if any mods or "total conversions" are in development.

Try tombraiderforums.com for starters.