I recorded a macro where I just select one day to see what it gives me and it's doing it the long\awkward way of asking for everything to be hidden but the item/date I have selected! The below code is simply me clicking on the filter and ticking one day.

ActiveSheet.PivotTables("PivotTable2").CubeFields(2).TreeviewControl.Drilled = _
Array(Array(""), Array("[Dates].[PeriodDates].[PeriodYear].&[2013]"), Array( _
"[Dates].[PeriodDates].[PeriodNo].&[255]"), Array( _
"[Dates].[PeriodDates].[PeriodWeek].&[2551]"))
ActiveSheet.PivotTables("PivotTable2").PivotFields( _
"[Dates].[PeriodDates].[PeriodYear]").HiddenItemsList = Array( _
"[Dates].[PeriodDates].[PeriodYear].&[2011]", _
"[Dates].[PeriodDates].[PeriodYear].&[2012]")
ActiveSheet.PivotTables("PivotTable2").PivotFields( _
"[Dates].[PeriodDates].[PeriodNo]").HiddenItemsList = Array( _
"[Dates].[PeriodDates].[PeriodNo].&[253]", _
"[Dates].[PeriodDates].[PeriodNo].&[254]", _
"[Dates].[PeriodDates].[PeriodNo].&[256]", _
"[Dates].[PeriodDates].[PeriodNo].&[257]", _
"[Dates].[PeriodDates].[PeriodNo].&[258]", _
"[Dates].[PeriodDates].[PeriodNo].&[259]", _
"[Dates].[PeriodDates].[PeriodNo].&[260]", _
"[Dates].[PeriodDates].[PeriodNo].&[261]", _
"[Dates].[PeriodDates].[PeriodNo].&[262]", _
"[Dates].[PeriodDates].[PeriodNo].&[263]", _
"[Dates].[PeriodDates].[PeriodNo].&[264]")
ActiveSheet.PivotTables("PivotTable2").PivotFields( _
"[Dates].[PeriodDates].[PeriodWeek]").HiddenItemsList = Array( _
"[Dates].[PeriodDates].[PeriodWeek].&[2552]", _
"[Dates].[PeriodDates].[PeriodWeek].&[2553]", _
"[Dates].[PeriodDates].[PeriodWeek].&[2554]", _
"[Dates].[PeriodDates].[PeriodWeek].&[2555]")
ActiveSheet.PivotTables("PivotTable2").PivotFields( _
"[Dates].[PeriodDates].[Day]").HiddenItemsList = Array( _
"[Dates].[PeriodDates].[Day].&[2013-02-24T00:00:00]", _
"[Dates].[PeriodDates].[Day].&[2013-02-26T00:00:00]", _
"[Dates].[PeriodDates].[Day].&[2013-02-27T00:00:00]", _
"[Dates].[PeriodDates].[Day].&[2013-02-28T00:00:00]", _
"[Dates].[PeriodDates].[Day].&[2013-03-01T00:00:00]", _
"[Dates].[PeriodDates].[Day].&[2013-03-02T00:00:00]")