it's really important for me:( nobody?

Hello! I would like to install .inf modem files in windows. I've searched MSDN but i've found only modem .inf structure, nothing about installing them. I already read some Setup API functions ( SetupDi* ) but I'm not sure those are the ones i need. If so, which of them are needed to do this? or how to do this? I really don't have any ideas :( i hope you can help me, grizz