Package path with user control

How does one include a path relative to the home directory?
When I make a package, how would I refer to its location.
I want the user to change the directory to where he has put the
package code.

(defcustom lena-waypt
  "/home/borgia/Opstk/src/hist/hist-1.0/lena/"
  "Directory path to the Lana component."
  :type 'directory
  :group 'lena
  :set (lambda (symbol value)
          (set symbol (expand-file-name value))
          (message "Lana path set to: %s" (eval symbol))))