Not too sure about using actual MIBS, but I would snmpwalk the ups ip and then check the oid against an online oid database for the ones i need.
Not sure about posting external urls here, but this is the one i use....
this is also handy
It is a bit time consuming if you are not too sure of the oids you are after, but the manufacturer might well have them listed on their website, but this is how I have configured my charts and it works well enough.
Hope this helps.
Apologies if it does not!!