Hi,
Another approach is to create a custom calendar for a "per diem" resource.
Set the "per diem" resource's calendar to this custom calendar. If you need
to set a "per day" cost to this resource, you can set the "type" to either
Work or Material noting that a Material resource cannot have max units. For
a "work" type, set the standard rate to "$25/day" for example. For a
"material" type, you can enter "$25" in the standard rate field. When
assigning the "per diem" resource to a task, set the number of units to the
number of days you will designate as per diem days. You can also manually
enter the number of units in a task usage view and set the timescale to
"Weeks" and "Days" then enter "1" (for units) for each day needed.
Hope this isn't too confusing.
Best of luck!
Ian