How to populate an array from an external text file

Hi all,

This is probably the simplest question in the world for some of you, but I've looked around for ages and can't get a simple answer, so I thought I'd ask you lot...

What I need is for Unity to ask the user for a path, to then load the text file from that path, parse it and then populate a javascript array with the contents. I don't have the foggiest which function or method to use - I've found suggestions to use System.IO but have no idea how to implement that... Apparently using TextAsset's no good for runtime operations so that's probably out - or is there an easier way?

Thanks guys (and gals!)