TOPIC:

What is the correct way to perform this upgrades on a working system?

Manually install the RPMs from:
halizard.org/release/drbd/RPM/
halizard.org/release/ha-lizard/
halizard.org/release/iscsi-ha/

Are there any scripts to perform this upgrade?

Excuse the delay in responding to this post. Detailed steps can be found in this post (which includes a script to handle the post-upgrade steps)
www.halizard.com/forum/software-support/...xcp-ng-8-0-beta#1955