lsof can be gotten at http://aixpdslib.seas.ucla.edu/packages/lsof.html
(that according to Bruce on 12-27-2002)

-------------------------------------------------------------------------------------
Notes on Building lsof 4.33 on 6-15-1998.

- mkdir lsof ;cd lsof
- Get lsof from ftp://vic.cc.purdue.edu/pub/tools/unix/lsof/lsof.tar.gz
  Warning!!  I had to do this a half dozen times before I got the whole
  tar file over.  Network problems??  If a gzip -d < lsof.tar.gz | tar tvf -
  works ok, then you've probably got it all.
- gzip -d < lsof.tar.gz | tar xvf -
- tar xf lsof_4.33.tar
- Configure aix
  - Answered "y" to all their questions except for "Do you want to customize?"
- make

Unfortunately, when running as root, I get an immediate Segmentation fault(coredump),
while Dale's version at /local/bin/lsof seems to work, but a /local/bin/lsof -i -n
gets a bunch of "... can't read inpcb at 0x180aee44" messages, so that one isn't
completely healthy either.