Hi Anton,
Welcome to theSwamp forums.
I can't remember if EATTEXT was part of A2K2, but if so then you can just call it as any other built-in command.
If you're referring to Express Tools' ATTOUT command then it's based on an AutoLISP routine with the command prefix "C:".
You can call it from within your own AutoLISP routine with (C:ATTOUT).
For example
(defun runMyAttExtraction (/ attm)
;; do something ... e.g.
(setq attm (getvar "ATTMODE"))
(setvar "ATTMODE" 2)
;; call ET's ATTOUT
(C:ATTOUT)
;; do something else ... e.g.
(setvar "ATTMODE" attm)
)