You can install both apache and IIS on same port if the system has two IP address. You may install IIS and apache server in normal way. IF IIS is started prior to Apache, IIS will take all the IP address and apache cannot start on the same port. Do fix this, we need to tell IIS to bind only one ip.
You need HttpCfg.exe utility to do this tak. It is available by default on Windows Server 2003 but if you’re using Windows XP you can install HttpCfg.exe as part of the Windows XP Service Pack 2 Support tools. Then open a command prompt and type the following, replacing xxx.xxx.xxx.xxx with the IP address you’d like to bind to IIS:
C:Windowssystem32>httpcfg set iplisten -i xxx.xxx.xxx.xxx