Install the database instances on the shared storage only on the one node where the instance's home directory is currently mounted. You can choose to install single-partition instance or multi-partition instance. You can use IBM's db2setup tool.
Keep in mind the following when you install:
When you use the db2setup, do not select the option to Auto start DB2 instance at system boot in the DB2 Instance Properties window. Note that this option does not exist on all DB2 versions. VCS needs to bring up the resources for the DB2 instances in a specific order before it brings the instance online.
The instance's home directory is a mount point on the local system.