If you don't already have a .latex2html-init file, simply type
cd webpubdemo cp dot-latex2html-init ~/.latex2html-initIf you do have a .latex2html-init file, you can probably just append the new one to your existing one. (Insert it just before the last line if it is simply ``1;''. Such a line provides a ``true'' return value for Perl.)
Since latex2html init files are executed as Perl scripts, appending the new one may override some preferences you had set. However, you should be able to try out the new preferences and then delete the new lines you don't want.
No changes to dot-latex2html-init are required for simply trying out a build of the webpubdemo examples. However, for future use, the following edits are desirable: