I think I found the solution.
I just installed apcupsd via YUM and started the service. It looks like the default config is finding my UPS. I'll read the docs and see if I need to tweak it for shutdown when the battery is low.
Code:
[root@server ~]# service apcupsd start
Starting UPS monitoring: [ OK ]
[root@server ~]# service apcupsd status
APC : 001,035,0869
DATE : Sun Aug 13 22:26:17 HST 2006
HOSTNAME : server.ltsp
RELEASE : 3.12.2
VERSION : 3.12.2 (18 January 2006) redhat
UPSNAME : server.ltsp
CABLE : USB Cable
MODEL : Back-UPS XS 1200
UPSMODE : Stand Alone
STARTTIME: Sun Aug 13 22:26:14 HST 2006
STATUS : ONLINE
LINEV : 119.0 Volts
LOADPCT : 11.0 Percent Load Capacity
BCHARGE : 100.0 Percent
TIMELEFT : 53.8 Minutes
MBATTCHG : 5 Percent
MINTIMEL : 3 Minutes
MAXTIME : 0 Seconds
LOTRANS : 097.0 Volts
HITRANS : 139.0 Volts
ALARMDEL : Always
BATTV : 26.9 Volts
LASTXFER : Low line voltage
NUMXFERS : 0
TONBATT : 0 seconds
CUMONBATT: 0 seconds
XOFFBATT : N/A
SELFTEST : NO
STATFLAG : 0x07000008 Status Flag
MANDATE : 2006-02-22
SERIALNO : xxxxxxxxxx
BATTDATE : 2001-09-25
NOMBATTV : 24.0
FIRMWARE : .g1 .D USB FW:g1
APCMODEL : Back-UPS XS 1200
END APC : Sun Aug 13 22:26:20 HST 2006
[root@server ~]#
==Update==
Looks like the defaults are pretty good.
/etc/apcupsd/apcupsd.conf
Default for shutdown is 5% calculated battery level (and/or) below 3 minutes calculated battery remaining. Dam that was too easy!