gtk-list-store-set (store iter &rest values)

store -- a gtk-list-store object
iter -- a gtk-tree-iter row iterator
values -- the values to set

The gtk-tree-iter iterator for the row being modified.

Sets the values of one or more cells in the row referenced by iter. The variable argument list should contain the values to be set.

(let ((model (gtk-list-store-new "gchararray" "gchararray" "guint")))
  ;; Append a row and fill in some data
  (gtk-list-store-set model
                      (gtk-list-store-append model)
                      "Hans" "Müller" 1961)
   ... )    

The Lisp implemenation does not support pairs of a column index and a value, but a list of values. Therefore, it is not possible to set the values of individual columns. See the function gtk-list-store-set-value for setting the value of single columns.