Defining Variables Using Variables

I'm trying to loop through a range in excel from access, checking where the titles (in Excel row 1) match with the fields (in a recordset in Access that is passed to the function) - and where they do, I want to dimension a variable to hold the column number - I'm not sure it's possible, but I'd be interested to know either way. The line I'm asking about is at the bottom of the code - the rest of the code is just to give context...

Sub ImportGeneric(rsImported As ADODB.Recordset, rsConfirmed As ADODB.Recordset)
Dim fd As FileDialog
Dim xl As New Excel.Application
Dim wb As Excel.Workbook
Dim ws As Worksheet
Dim iFilePicked As Integer
Dim strFilePath As String
fd.Filters.clear
fd.Filters.Add "Excel files", "*.xls"
fd.ButtonName = "Select"
iFilePicked = fd.Show
If iFilePicked = -1 Then
strFilePath = fd.SelectedItems(1)
Else ..................