Well, you could just use the /play command on it's own... for example, /play your-nickname file.txt 2000, you can type that in the editbox itself without a script.
If you want to do it for when you type, for example, !list to the channel however, then use the ON INPUT event as I described earlier, for example:
if (!list isin $1) play $me !list.txt 2000
Then when you type !list yourself, you'll play the specified file to yourself. Do remember to change #channel to the channel name you want it to work on.