For a std upgrade from 10.1 to 10.2, shut down the CRS stack on all nodes, & unlock the CRS home using the script [B]mountpoint/clusterware/upgrade/preupdate.sh. When u run OUI & select the option to install Oracle Clusterware on a subset of nodes, OUI installs Oracle 10.2 clusterware into the existing CRS home on the local & remote node subset.
When all member nodes of the cluster are running clusterware 10.2, then the new clusterware becomes the active version.
You can now upgrade ur db from 10.1 to 10.2. If u're planning to use ASM for storage, then i'll suggest u install & patch the ASM from 10.2.0.1 to 10.2.0.3 & do the same for the oracle software separately. I found it easier trouble shooting separate ASM/software installs than first laying down the software & using dbca to create an ASM instance.

Good luck...