Changing weekday in workday formula

Hello,
When i am working in excel file i have troubled in work day calculations.May you help for getting a solution
in changing the weekday in workday(start date,no of days,holiday) formula.
For eg:
Start date: 02/02/2009
No of days to go:70
Holidays:05/02/2009

Formula tobe used:
workday(start date,no of days,holiday)

Here i want to change the default nonworking days(sat & sun to only wednesday)
regards
Subbu