Service waiting for external parameters

Question

Hi, i'm new in .net and most in C#.

Have a Service developed but i need to upgrade it.

The service must write a dinamic xml.
Why dinamic?,  well because the service will read a configuration file from a external system like a cfg file or txt file or ini file.

Anyone did something like this ?

Exist something like standard process to do this ?
Any info will help me

thanks in adv