Are you using Bento 2 and FileMaker Pro as well?
If your using FileMaker Pro there is a plugin called FM-iCal Connector that can prompt you with alerts.
More info here:
Or if you are just using Bento 2 itself, your question is better answered on the Bento Forums.http://forums.filemaker.com/fmbnto/
Thank you for your post.
The advice from "bwest" is correct (Thank you!). That is, this is more suited for the Bento forum. However, since you already asked, here is some information that may help.
Although Bento 2 integrates with iCal, Bento 2 does not have access to the Alarm field. A number of other users on the Bento forum also want the ability to set an alarm. One of the reasons this is not possible at this time is because you can have multiple alarms per event, and without creating a new list field type solely for an iCal alarm, which occurrence of an alarm would be chosen? The first? The last?
In any case, I have forwarded your suggestion to our Bento Development and Product Marketing departments for consideration in a future release.