Before you can start to check your packages with Lintian, you'll have to install the lintian Debian package.
Alternatively you can checkout Lintian from the source repository and use that directly. By setting LINTIAN_ROOT (or using the --root option) lintian can be run from the source directory as if it had been installed on your system.
The only known caveat of using Lintian from the source directory is that Lintian requires a C.UTF-8 (or en_US.UTF-8) locale to correctly process some files. Lintian 2.5.5 supports using the C.UTF-8 locale from the libc-bin in Debian Wheezy.
If either your version of libc-bin or Lintian are too old, you can work around this issue by generating an en_US.UTF-8 locale. Alternatively, installing a copy of lintian should solve this, as older versions of Lintian generates a private locale at install time. Note, older versions of Lintian can only use the en_US.UTF-8 locale.