Well to load the script you simply put the script into IDA-s python directory and then import the module.
So if this script is called ecutools.py you type "import ecutools". After that you can access the functions as a module - ecutools.xxx
You can also reload modules - reload <module>.
Whether you can paint an UI or not, I don't know. It depends if IDA allows you to import TK and create TK widgets.
However the preferred way to trigger it by UI is through adding items to the edit->plugins menu. You can find some info here:
http://www.hexblog.com/?p=120Personally I prefer console commands, so I just import the module and pass arguments to it