Urgent and very important information in vb6.0

[siva.almighty]

hello,
i am working on vb6.0. first i added two integers in vb6.0. And i made setup file of that code and i tested the setupfile which is working fine. Now i made this setup in a remote system. Now i want to upgrade the code, so that it adds two decimal numbers, and this i have to send only the code package that was upgraded, not the setupfile. And the installed exe file has to be updated automatically so that it will be working fine for decimal numbers also.
Example: For windows when we update using service packs, there is no need for us to setup the whole windows, the package automatically fits into windows.
So how can i do the above upgrading of my code, i mean how should i design the code(package) so that it automatically upgrades from integers to decimal numbers. if possible plz send me some code related to it(for understanding);
So,hope you understood the query. Any doubts please mail me. Thanks in advance.
yours,
siva.