I use code like this. This is to insert in model space, scaled based on DIMSCALE.
(defun setpower ()
(if (null (tblsearch "layer" "power"))
(command "-layer" "make" "power" "color" "cyan" "power" "")
)
(setvar "clayer" "power")
)
(defun enco_insert (symbol / ds)
(setvar "cmdecho" 0)
(setpower)
(setq ds (getvar "dimscale"))
(prompt "\nSelect insertion point... ")
(command "_insert" symbol "PS" ds pause ds ds pause)
(princ)
)