Have you looked at Bamboo's ADE in the EasyLanguage forum? Currently, that's the best (read that only )way to use external data in TS. Upcoming versions are supposed to open TS up again to 'non-proprietary' data streams....
You could take a look at owndata http://www.tssupport.com/products/owndata/
Bit pricey, but it looks like it handles ascii files as well as a few different data feeds.
Steve