I have been asked to produce a histogram for a plan held in P6.  While I am normally quite happy to run histograms the particular plan I have been asked to do it for is not what I would call a "plan" its more a management resource tracker.  I cannot change it much - its something I have inherited and while I know its not "proper planning" its what I have to go with.

First to give you an idea of the "plan".  The WBS is set up by division of company, The resources are set up as Resource ID namae = persons name, and the role as their current role.  There are columns to show project assigned to with details listed of the project the member of staff is working on, and a further column for percentage allocation.  This means a report can be run off to show Joe Bloggs works 40% of his time on project A, 40% of his time on project B and the other 20% are unallocated so management can match his skill set up to new work arriving.

My issue for producing histograms is that there are no labour units assigned to the project, the assignments tab has no data.  There are start and finish daes, but the original duration is incorrect as the project has "started on" applied and then the dates have been moved so original duration is incorrect.

My initial thoughts were to write some UDF and global changes to input some hours.  I was thinking set up a callendar as 10 hour day (as this works easier for the % allocation) and then do a sum of duration * 10 = budgeted labour units which would pull through to histogram and I would use a 50 hour week to produce chart (I would normally produce a histogram in excel).

Has anyone got any idea of where i should start on this?  I see my iinitial ssues as:

Updating the duraion to show the duration post date changes

Inputting budgeted labour units

All advice gratefully recieved, thank you.