custom-buffer-create-other-window is an autoloaded compiled Lisp function in `cus-edit.el'.

(custom-buffer-create-other-window OPTIONS &optional NAME DESCRIPTION)

Create a buffer containing OPTIONS, and display it in another window.
The result includes selecting that window.
Optional NAME is the name of the buffer.
OPTIONS should be an alist of the form ((SYMBOL WIDGET)...), where
SYMBOL is a customization option, and WIDGET is a widget for editing
that option.