If by "acknowledge alerts" you mean "mark events as reviewed," you can bulk-select events in your view (say, from a view containing all events from a particular data source) using either Shift or Ctrl to select multiple consecutive or non-consecutive events, respectively. Then, from the Menu dropdown, select Mark as reviewed > Selected.
I don't have my notes handy but I think you can do this via command line. I'll reply back tomorrow with a database command that you can try and modify to do what you need.
To get into the database on the ESM
DISCLAIMER:: Please run any of the below at your own risk. We used some of this pre-production to clear things out from testing.
## to show columns triggeredalarm table
show columns from triggeredalarm
"This will dump out the columns and give you things to use in your search for conditions"
FROM MY NOTES:::
##### Delete Alarm in bulk
delete from triggeredalarm where triggerdate < '09/13/2014 00:00:00'
#### acknowledge alarms in bulk, make sure you confirm the userid number
update triggeredalarm set status=1, ackdate='10/02/2014 00:00:00', ackuserid=15 where triggerdate < '09/30/2014 00:00:00'
## This opentime logic can go eith way < or >
update casemgt set status=2, closetime='11/27/2013 18:10:48.000' where opentime < '08/12/2013 16:10:36.000'
## To check how many are not closed
select count (*) from casemgt where status <> 2