This function converts a list of values into an association list (alist).

(defun list->alist (items)
  "Convert a list into an alist."
  (loop for item from 0 to (1- (length items)) by 2
     for key = (nth item items)
     for data = (nth (1+ item) items)
     nconc (acons key data nil)))

Basic example

Running list->alist on this input:

(list :key1 "value1" :key2 "value2" :key3 "value3")

produces the following output:

((:key1 . "value1")
 (:key2 . "value2")
 (:key3 . "value3"))