Thanks BIGAL!
So I've completed this Lisp how I'd like it to work. Thanks for all the help peoples! The lisp is below and the block is attached for anyone that wants to use!
;;;RTAG(defun c:RTAG\ (/ pt1 pt3 rx ry pt5) (setq atrq (getvar 'attreq)atd (getvar 'attdia) ) (setvar 'Attreq 1) (setvar 'attdia 0) (initget 1) (setq pt1 (getpoint "\nFirst Room Corner: ")) (initget 1) (setq pt3 (getcorner pt1 "\nOpposite Room Corner: ")) (setq att1 (getstring "\nEnter Room Name Top")) (setq att2 (getstring "\nEnter Room Name")) (setq rx (abs (- (car pt3) (car pt1)))) (setq ry (abs (- (cadr pt3) (cadr pt1)))) (command "_INSERT""Tag_Room-Dim""_scale" "1"(polar pt1 (angle pt1 pt3) (* (distance pt1 pt3) 0.5))""att1(strcat "%%U" att2)(strcat (rtos rx 4 0) "x" (rtos ry 4 0)) (setvar 'Attreq atrq) (setvar 'attdia atd) (princ))
Tag_Room-Dim.dwg