User32.dll

Detect Key Stroke

link - http://www.cpearson.com/excel/keytest.aspx

Private Declare PtrSafe Function GetAsyncKeyState Lib "user32" (ByVal vKey As Long) As Integer 

Private Const VK_F9 = &H78 

Sub WaitUntilF9Key() 
Do Until GetAsyncKeyState(VK_F9) 
    DoEvents 
Loop 
MsgBox "Hello World" 
End Sub