At ICFP 2005 Greg Pettyjohn presented a paper that he co-wrote with
John Clements, Shriram Krishnamurthi, Matthias Felleisen, and myself
that shows how to implement first-class continuations without
requiring full stack inspection. The paper describes how one might
implement first-class continuations in Java or C# by transforming the
source code rather than hacking the underlying VM.
Since the paper needed to be really brief, the details of the
transformation were omitted. I have put up a much more detailed
description (with code samples and everything) at
http://home.comcast.net/~prunesquallor/stackhack4.html
The ICFP paper can be found at
http://www.ccs.neu.edu/scheme/pubs/icfp05-pcmkf.pdf