Since you also might need to modify powerd.c to raise and lower the
correct lines, you might also need the numeric values of different
terminal signals. The can be found in
/usr/include/linux/termios.h, but are reproduced here for
reference. Since they could change, you're best off confirming these
values against said file.
/* modem lines */
#define TIOCM_LE 0x001
#define TIOCM_DTR 0x002
#define TIOCM_RTS 0x004
#define TIOCM_ST 0x008
#define TIOCM_SR 0x010
#define TIOCM_CTS 0x020
#define TIOCM_CAR 0x040
#define TIOCM_RNG 0x080
#define TIOCM_DSR 0x100
#define TIOCM_CD TIOCM_CAR
#define TIOCM_RI TIOCM_RNG
Note that the 3rd column is in Hex.