Until today it's still making noise but I'm just bearing with it even though there's a new clutch pedal waiting for my installation at SC...

Your post prompted me to have a look at the pedal assembly closely. After some fiddling I managed to get the noise to go away, for now. Here's what I did:

1. Remove fuse box cover next to driver's door

2. Remove panel below steering wheel. To do this, remove the two screws, the rest is held by clips. Pull on all sides gently until it comes out. Disconnect the power mirror control, OBDII port and the bonnet release lever.

3. Now you can see your clutch pedal assembly as in the picture below. I managed to remove the locking pin and the main pin holding the clutch pedal to the plunger, but the big 14mm nut on the top right corner was too tight for me remove and besides the space is quite tight and confined and you have to bend in an awkward manner to access this position. You need another 14mm wrench to hold the bolt on the other side as you try to loosen the 14mm nut.

Anyway, I tried lubricating the main pin but the noise was still there. Then I tried to feel the mechanism behind the main pin and felt it was already very greasy. So I think I must have managed to spread a bit of the excess grease onto the contact points, at the place described "Lubricate in here" and after putting back the main pin and the locking pin, the noise was gone. If you have really long 14mm wrenches you might be able to remove the big bolt and lubricate the area properly.