how to mimik a main() function to start a program with entry point?

[krishnakant Mane]

hello all.
I have one simple query and may be that's to stupid to answer but I am
not finding the answer any ways.
I have a set of modules in my package and out if which one is my
actual starting point to my entire program.  say for example I have an
entire database application ready and I want a main (as in java or c)
to initiate the program and may be bring up a login screen and then
pass the control on to the main window.
if I am giving raw source code that is easy because I will tell user
to run the command ./xyz.py which has that function.
but if I freze it into an executable with py2exe for example , how do
I solve this problem?
thanks.
Krishnakant.