I haven't coded in VBA in a while so I'm not 100% on the syntax but I believe this will work for you. What I did to get the correct alpha value was add 65 (ASCII decimal code for A) to your number which will get me the correct decimal value and brought that back to a character.
Expand|Select|Wrap|Line Numbers
Dim N As Integer
Dim Alpha As String
N = 776655
Alpha = CStr(N)
For i As Integer = 1 To Len(Alpha)
Mid(Alpha, i, 1) = Chr(CInt(Mid(Alpha, i, 1)) + 65)