Hi
See attached Doc for procedure - section 3330B26 (clutch pedal R&R) from the 02-06 elearn WSM available from the FF downloads section.
I don't think it would be necessay to drain the complete brake fluid from the brake master cylinder reservoir as they say.
I would just clamp the rubber supply line in the engine compartment from the brake master cylinder reservoir with vice crips/G clamp etc which feeds the clutch master cylinder (they call it a pump) located up under the dash with the pedal.
After replacement you will then need to bleed the clutch hydraulic system which is also covered in the Doc but they describe the procedure using a pressure bleeder, but would also work using the manual bleeding method.
Cheers