It would seem like you will
need to have Python, Imlib2 and Fluxbox installed. Check to make sure you've got them:
whereis python
whereis imlib2
whereis fluxbox
Also, I would try:
locate python | less
locate imlib2 | less
locate fluxbox | less
Just for good measure. To get out of "less" hit your Q key. Once you've found that you've got them installed then you're good to go with your installation of that program. The others are "options". If you want them, download them and install them if you don't already have them. To find out if you have them or not, do the same commands as above, but substitute the names of the options instead.
Also, check out
www.linuxpackages.net for Slackpacks (tarballs that end in .tgz are packages designed for use with Slackware's pkgtool.
Hope this helps.