Here are changes I made to texi2roff 2.0 from cs.toronto.edu.
I have the original source if you have problems applying my patches.
I added most of the changes to -me only.  Do not use the -mm or -ms options.

1) Support for variables with @set, @clear, @ifset, @ifclear, and @value.
   Some manuals use variables for holding the program name or for conditionals
   to print different versions.

2) Ignores the first line of input if it starts "\input texinfo".

3) Ignores the text after comments.
   Some manuals had commented commands that texi2roff was trying to parse.

4) No longer crashes on @include commands on ignored lines.

5) Support for most texinfo commands including texinfo version 3.9.
   @multitable/@tab does not make clean tables.
   Some of the character codes, like @O{} for a slashed O, are recognized
   but print an ascii representation.

6) Does not support @macro.  If a texinfo file has macros, use "makeinfo -E"
   to expand them before running texi2roff.

7) Improved error checking.  texi2roff now prints warnings for mismatched
   @ends, even on inactive lines, and for invalid entries in its internal
   tables.