Jeff,
Of the two approaches,
pure tcl fastcgi support aka 'portable.nsd' orAOLServer supporting the fastcgi protocolI think the latter would take less time. Since pnsd's current issues have stumped me (debugging query parser, implementing list builder and ad_form in pure tcl), I can't take a guess at how much longer it would take. I think they're solvable, but for someone closer in tcl ability to Michael Cleverly.
For adding FastCGI support to AOLServer, there are a large number of fastcgi implementations, including several in C (see fastcgi.com) and one or two in TCL
http://sourceforge.net/projects/tcl-fastcgi/
Looking at the example code, I'm guess you're talking < 1K SLOC to implement this, most of which is already written. It is probably on par with implementing a new database module.
I don't think that's 3-6 months, but maybe if AOLServer is really hard to hack on. Which I doubt.
As Patrick points out, this approach puts AOLServer on par with how most Java Servlet engines run -- out of process and speaking through a socket to some in-process connector. However, from my own experience with fastcgi/apache, configuration will be much closer to mod_rewrite+mod_proxy than mucking with xml config files to make your java app server happy.
Crucially, going this route also gets you IIS support for free (where mod_proxy is not an option).
As to who can do it... I think anyone who could extend AOLServer would be qualified to do this.
