You have to get the most recent distribution of dlh at any of the following places:

• At ftp://ftp.cs.arizona.edu/pub/dlh/, where old and new versions are available; this is the official release site as it is maintained by David Mosberger-Tang, original author of dlh.
• From the Carnegie Mellon University mirror site at http://www.cs.cmu.edu/~fgcozman/Miscellaneous/Dlh/dlh.tar.gz, for the last release.

Now that you have dlh, you can go ahead and install it.