Since you are booted into Windows (when using Boot Camp), don't you just use the control panel in Windows or preferences in Excel to designate what F2 does?
Kenichi Watanabe wrote:
Note: There is a setting in System Preferences Keyboard pane Keyboard tab that makes the F-keys act as regular F-keys (instead of the special function keys) under Mac OS X. You should check in the Windows control panels to see if there is a similar setting on the Windows side that does the same thing. Then, you may not need to use the fn key along with F2 to do that function.