I've never had to do it on DH yet. But this explains how to install a completely different program on DH. The thing is, some of it will apply to yours as well.
https://netpbm.svn.sourceforge.net/svnroot/netpbm/stable/doc/INSTALL - that explains the basic install process of a NetPBM install. You'll need to mix and match with some stuff from the FFmpeg one above. mainly on the configure, --prefix=$HOME --enable-cross-compile --enable-shared should be the jist of it. I've never installed NetPBM that i can remember, so im not sure on that working or not.
for the subversion part of the install, you have 2 routes, Advanced or Stable.
svn checkout http://netpbm.svn.sourceforge.net/svnroot/netpbm/advanced netpbm
replace advanced with stable on preference.
http://netpbm.sourceforge.net/ - that can lead you into most of it. They might be able to explain it better there then I can here. But that should cover it. (ffmpeg gives you the rough outline of installing your own programs, the install tells you how to run a basic netpbm install and the svn you need to download the latest source)
Hope that helps a bit,