Yes, you can create text-symbols directly in ADT since SAP NetWeaver 7.31 SP14 or 7.40 SP08.
For creating a text-symbol you should utilize Quick-Assist Eclipse functionality:
Write text-XXX
piece in any valid statement, e.g.
WRITE: text-009.
- Place cursor on it and press Ctrl-1 or select Quick-Fix in context menu, and you will be suggested to create text in text pool.

What concerns selection texts and list headings, no, they are still to be edited via GUI.
However, SAP implemented small menu entry for quick access to this function. Just hit context menu on any place of the source and select Open others->Text element.
