[texworks] Trying to build TeXworks on Xubuntu 8.10

[Karl Berry]

    >> install-info: No dir file specified; try --help for more information.
    >> dpkg: error processing comerr-dev (--install):

Is the exact install-info invocation shown?

I expect that the underlying problem is that Debian install-info is
different from GNU (texinfo) install-info.  Perhaps you are getting GNU
i-i, say from TeX Live, and the package is certainly expecting Debian.
If so, there's an easy solution: (re)move the TL install-info.