If you add a chat tab with just /tells and filter the /tells out of your other windows, I believe the tab will highlight if it has unread /tells. Granted, then you're less likely to see them in the main tab. It might still work with the /tells shown in the main tab, but I know that functionality is kinda there. Give that a try.

As for the LS-logon notification, I strongly doubt the framework is there to support it. Most of XI and XIV is oriented around pulling information, not pushing it to the client, and you'd need push notifications for that.