From source

Build sessiond, sessionctl, and the PAM module in release mode:

cargo build -p sessiond -p sessionctl -p pam --release

Install the binaries and PAM module:

install -Dm755 target/release/sessiond /usr/local/bin/sessiond
install -Dm755 target/release/sessionctl /usr/local/bin/sessionctl
install -Dm755 target/release/libpam.so /usr/lib/security/pam_sessiond.so

The consolekit feature enables the ConsoleKit compatibility layer. Include it when building if you need that support:

cargo build -p sessiond --release --features consolekit