I've written a how-to to get ISP manager to work with Arch Linux:
http://wiki.archlinux.org/index.php/HOWTO_ISPmanager
There are still some issues that should be resolved before ISP manager is production ready:
* Dovecot doesn't work correctly. Bug report:
Dovecot passwd lines are incorrect
* Webalizer doesn't work. I've opened a support ticket. ->
FIXED
Edit: added support for awstats
For the rest all seems good to go.
Glenn