A full install script is at: https://github.com/cyclestreets/cyclestreets-setup/tree/master/install-telluswhere/
However, the key requirements are as follows:
# Obtain the repo
git clone git clone https://github.com/cyclestreets/telluswhere.git
# Requires PDO SQLite
apt-get install php5-sqlite
# Useful for command-line interaction with database; see: http://sqlite.org/sqlite.html
apt-get install sqlite3
# Ensure the database directory and tmp directory are writable
chown -R www-data db/ tmp/