FL Instrument Cluster Swap with no SKC's
 

Can this be done?

I don't have the 4 digit pin for the current cluster, and I wouldn't think that a replacement cluster wherever its sourced from will come with one either.

I guess the pin number would need to be extracted from both clusters using something like VAG-Tacho, but can the pin number of the replacement cluster be extracted whilst connected to the car it's not currently paired with?.

You just need the SKC for the used cluster according to the Ross Tech wiki

http://wiki.ross-tech.com/wiki/index.php/Immobilizer

You will need login for new instrument panel or you can solder memory chip over from old cluster.