When you use Bricklink Studio with custom parts and want Studio to show you the available colours you need a meta command for the bricklink item number.
The metacommand is the following(5272pb01 is an example part number):
It has to be placed directly after the "0 Author:" line in the header to work. Otherwise you the default LDraw header can be used.
The metacommand is the following(5272pb01 is an example part number):
Code:
0 BL_Item_No 5272pb01