Why do you need third party tools for backup your VMs?
If you want to use any command line tools, you could use "vzdump" to create backups. More you can read on the wiki: http://pve.proxmox.com/wiki/Backup_and_Restore
Then use the integrated backup function in Proxmox and let the backups upload in a SAMBA share (or something like this), where your people can access it.
The vzdump tool offers much options you can use. The best would be, if you take a look on wiki page of vzdump:
Proxmox also offers a intergrated backup site (If you don't already know it) - it's on "Datacenter" in the "Backups" tab. This also uses the vzdzmp utility.