The S13's came with ABS so might be worth looking for one being broken on SXOC.
I guess you'd need...
Wheel Speed sensors
ABS ECU (If it's even separate)
ABS Pump
Might need the Servo and Master Cylinder
A few lengths of Brake line and tools to make the ends up
God knows how you'd go about it but anythings possible if you've got the time and money
