How to Change the Cluster Service Account Password

Changing Window 2003 Cluster passwords has been simplified and is relatively easy to do now. An there is no need to bring the nodes offline as in previous versions.

To change the Cluster service account password with Cluster.exe, type the following command from a command prompt to list all of the available parameters:
CLUSTER /changepass /?

Samples
Note: In the following samples:
EASTCLUSTER is a cluster name.
WESTCLUSTER is a cluster name.
NEWpassword is the new password.
OLDpassword is the old password.
To change the Cluster service account password for a single cluster, use the following syntax in which the password for EASTCLUSTER would be changed to NEWpassword from OLDpassword:
cluster /cluster:EASTCLUSTER /changepassword:NEWpassword,OLDpassword

Note: If you do not specify NEWpassword and OLDpassword, you are prompted to enter them after you press ENTER.

To change the Cluster service account password on multiple clusters, you need to reference the additional cluster. For example, to change the password for WESTCLUSTER in addition to EASTCLUSTER, you would use the following syntax:
cluster /cluster:EASTCLUSTER,WESTCLUSTER /changepassword:NEWpassword,OLDpassword

This KB Article goes into details on the whole process.