yes, but they have to be a system user.
I created a new user in webmin using lynx (called cheesy), then grepped /etc/webmin for his name to see where he was mentioned and what had been added - it's a good learning experience.
x = uses the users system password
hashedpassword = the actual password for non-system user. (and no, I haven't worked out how to calculate them)
Now you need to specify what they can access.
vi /etc/webmin/webmin.acl (if it doesn't exist, create it.)
root: acl at autorpm backup bsdexports burner cdbackup cpan cron custom dfsadmin
dnsadmin download fdisk file firewall format fsdump hpuxexports inetd init inittab
lilo logviewer man mount net nettools pam passwd proc quota raid rinetd servers
sgiexports shell shorewall software status syslog time useradmin usermin webmin
webminlog xinetd updown
cheesy: backup init cdbackup burner passwd shell custom quota mount download
xinetd file fsdump lilo firewall raid logviewer net nettools pam fdisk cpan proc at
cron shorewall software inittab man syslog time status updown usermin useradmin
webminlog webmin servers acl rinetd
Keep each user part on one line (no returns), single-spaced. I've split it here to avoid screwing the LQ board up.
Most of the modules are obvious, I gave cheesy complete access (note, I don't use all the webmin modules, so I've uninstalled them - create a test "access all areas" user using lynx to see what yours would look like.
Restart webmin for the new user(s) to take effect.
Works on Webmin 1.110, but to be honest, using lynx is easier and faster on the command line, unless you're adding a lot of users through a script.
(and of course, YMMV).