Ask your admin to install it (using apt-get/aptitude).
If it needs to work with Debian's packages, you'll need some other dev packages as well.
libpq-dev only includes the header files and C libs to link with libpq.
You would need to install everything (including other dependencies) from source to make it work (without having root).
Is there a unique procedure how to install from source code if no instructions are given?
No, but it's usually something like: