Last "activity" date on an opportunity

Hi there -

There is an article about how to use Sugar Workflow Management to record a "last activity" date on an Opportunity whenever a meeting, call, or task occurs.  Workflow Management is being replaced by BPM so we want to do the same thing with BPM.

Another forum user submitted a post saying that they had figured out how to do the same thing with BPM - but hasn't responded when we asked "how"?

Can anyone help?  We know we'll create a "last activity" field on the Opportunity and then update it whenever one of those events happens.  We'd want to update the last activity field whenever a call or meeting is "HELD" or a task is "COMPLETED" and figure we need 3 process definitions.

It's easy enough to trigger an event in BPM when one of those statuses changes but we can't figure out how to update the last activity field in the opportunity that's related to the call, meeting, or email.

Any assistance would really be appreciated.  If there are manuals or articles with all of this explained, please let me know - I just haven't been able to find anything.

Thanks so much!

Bob