Upgrade from RH5.10 32 Bit to RH6.8 64 Bit

I have been asked to find out if it is possible to do an upgrade on our Enterprise 5.10 going from 32 Bit to Enterprise 6.8 64 Bit.

To complicate this, the system is dual server cluster using High Availability and a Fibre SAN for the drives.

All of the drives are in the storage array and connected via Fibre. Below is the structure of the drives which are all mirror sets. / /boot /dev and /drv2 are all on the same mirror set.

/dev/mapper/VolGroup00-LogVol00
127G 20G 102G 17% /
/dev/mapper/mpath0p1 99M 68M 26M 73% /boot
tmpfs 12G 0 12G 0% /dev/shm
/dev/mapper/drv2_vg-drv2_lv
50G 18G 33G 35% /drv2
/dev/mapper/drv3_vg-drv3_lv
247G 18G 217G 8% /drv3
/dev/mapper/drv4_vg-drv4_lv
247G 164G 71G 70% /drv4
/dev/mapper/drv5_vg-drv5_lv
247G 72G 162G 31% /drv5
/dev/mapper/arch_vg-arch_lv
247G 16G 218G 7% /arch
/dev/mapper/arch2_vg-arch2_lv
247G 467M 234G 1% /arch2

We are trying to do this so we don't lose our existing printers and users. The printers are all installed in the default location of /etc/cups, but the users have been modified to be on /drv2/usr. /drv2 mounts to which ever system in the cluster is active so the users are always available to either server. All other drives only mount to the live server.

Is it possible to do this as an inplace upgrade without having to recreate everything including the clustering?

Would there possibly be a way of migrating the users from one system to another if we should have to install on a new box not clustered, then upgrade our clustered system, and migrate the users back to the cluster?

Our applications and data are all stored on the other volume groups so this should be available just by mounting it to which ever system is live.