I am sorry your question is not very clear to me. Can you explain what you are trying to do exactly, right now I cannot determine if you are trying to find an installation log for an application or that you are writing an installation procedure which you
want to equip with logging functionality.
If it is the installation of an application you should specify the name of the application so we can help you.
If you are developing an application then you would be better off by asking your question on the developer forums, in the forum of the language you are writing in:
http://social.msdn.microsoft.com/Forums/en/categories/