assuming your 2nd column is column B of the sheet, you might want to do something like this:
Def var ExAppl as com-handle.
CREATE "Excel.Application" ExAppl.
ExAppl:Visible=true.
ExAppl:Workbooks:OpenText ( "D:\McData\Cust92\arprsagt.dat",,,1,,,,True,,,, ,).
ExApp:range("B:B"):NumberFormat =...