I recently did this job myself.

Very good advice to use lots of rags to soak up the fluid that heads for the
carpet !!
Old towels work great.
I purged mine very differently.
I installed the new master cylinder, attached the pipe from the  reservoir on
the brake master cylinder, then fitted the metal line that goes to the slave
cylinder but I left it loose at the fitting.
I filled the reservoir and waited until fluid started dripping onto my pile
of old towels. Then with the fitting about 1/2 turn loose, I pushed the pedal
slowly up and down by hand, watching the air and fluid come out of the
loosened fitting.   Eventually, only fluid comes out so the fitting can be
tightened up.   Its good to snug it while the pedal is still pushed down by
hand.
Essentially, this purges the master cylinder only, using the line fitting as
a valve.
I found it unnecessary to go underneath the vehicle and purge the slave
cylinder.
I had changed all the fluid out a few months prior so I didnt feel the need.
The clutch worked great and still does.
Cleaning up afterwards was a real pain as its impossible to keep all the
fluid out of the carpet.

Good luck,    Steve Cotsford