You also can build aptitude from source; however, this is probably not a useful exercise unless apt is already available on your system. If it is, you can install aptitude from source with the following steps:
Install the following pieces of software:
A C++ compiler, such as g++.
The development files for apt, typically available in a package with a name like libapt-pkg-dev.
The libsigc++ library, available from http://libsigc.sourceforge.net.
Last but not least, download the most recent aptitude source code, available from http://packages.debian.org/unstable/admin/aptitude. (scroll to the bottom of the page and download the “.orig.tar.gz” file)
Once all the required components are available, open a terminal and execute the command tar zxf aptitude-0.2.15.7.tar.gz to unpack the source code. Once the source code is unpacked, type cd aptitude-0.2.15.7 && ./configure && make to compile aptitude. If this succeeds, make sure you are the root user (by using su, for instance), then type make install to install aptitude on your computer. Once aptitude is successfully installed, typing aptitude at a command prompt should start the program.