Use timesheet and OLAP in 2007 but dont update plan

[Tom B]

I have an instance of 2007 project server where we want to use timesheet
capability to record time at the project level...no task detail...then use
the cubes to report on time reported. the dept. does not want the updates to
impact the project schedule...they want PM of project to control when tasks
get marked as complete.
they want to use all projects where resources are assigned, but do not touch
any updating to the plan. they want to report actual hours worked on a
project. I will then use the cube to generate views for resources on a
project by time, so they can feed data to finance. they also do not want to
have all the tasks show up in a persons timesheet...too much granularity,
they simply want to report on project time by resource

What steps do I need to take to accomplsh this? I think I need to know how
to set up
-my project plan
-the timesheet options
-OLAP cube view should be fine, once I get the data there.

I understand how to create the bulk timesheets, but need some assistance in
knowing how to set up the project plan and resource assignments and timesheet
options. can anybody outline the steps and concept?