The following video demonstrates on how to create a spice model of a component, from a .subckt file which can be acquired from the retailer.
following is a spice model file for a bridge rectifier ; mb6s
data sheet : MB6S_MCC
– Open LtSpice
– Browse for the file and open
– Once opened right click .subckt and create model and design your circuit.
-Ref : http://www.linear.com