Requirements:
1. PostgresQL built with the --with-CXX configure options (C++ wrapper)
2. PostGIS support in PostgresQL
3. Qt 3.0.x built with thread support
4. Optional - Qt PostgresQL driver (can be built with Qt or separately -- see Qt SQL docs)

To build Qgis:
1. Make sure your QTDIR environment variable is set to your Qt directory
2. Set PGSQL environment variable to point to your PostgresQL installation and make sure the libpq++
   headers are available in $(PGSQL)/include
3. Build qgis by typing: make

The qgis executable will be built in the ./qgis/src directory