I have skipped a lot of parameters, but here are the key parameters(outstat, instat) that you want to use to get the cluster algorithm on the train set and then to cluster the new set. You should work out the details by yourself.
proc fastclus data=train outstat=outstat ;
var ClusteringVariables;
run;
proc fastclus data=new instat=outstat ;
var ClusteringVariables;
run;