Not sure if aptitude uses apt or if it's a separate package
installer... it seems to be on my system, so I guess it's on there by
default. Should be worth a shot.

If not, you may want to look at finding source code for it and
installing from that - I don't think you need apt to compile. However,
I did not dig up any source code for it after a bit of a Google search
and you may also run into the problem that you don't have the required
files to compile it. In that case, the best I can tell you is make sure
your data is backed up, and reinstall the system.