Turn paths into guides with the right click menu "Make guides" like in Illustrator.
Pretty self explanatory. It's very useful for example if you need a marquee or an odd shape to serve you as a guide and most importantly, the snapping in InDesign between a line and a guide is so different and so hard to snap to a path.
Tobias Wantzen commented
Thanks for this hint, Bob, the script is fine, but when I first read this feature request, I saw circled or diagonal or rectangled guides in InDesign made out of a drawing.
Bob Rubey commented
There is a script that can help with this: http://kasyan.ho.com.ua/convert_object_to_guides.html