All you need to do is put mirc.ini into your mIRC install folder and you'll be fine. However, it would be strongly recommended to use $scriptdir to get to the right location. Or, if this will only be used by you, just hardcode the path (c:\whatever\) instead of using a relative path.
If your script to load something is already loaded, then $scriptdir will point to the same location and you can easily load things that way. If you want to load from the edit line, then you need to include the full path or have the script (or relative path) start out in the same location as mirc.ini.
You can verify which mirc.ini you're using by typing //echo -a $mircdir in your edit line. Remember that you need to close mIRC before putting mirc.ini into the install folder (or restart it afterwards) for it to start using that mirc.ini.
