load Slideshow from Custom field

Hi there,
I installed and configured CustomPress and it works very good. Now I want to add pictures from the WP Media and show them as a slideshow.

I use Visual Composer and can load a Posts Slider from there. If possible it would be great to load this (or a similar) Slider from a custom field.

Thank you very much and best regards.
All the best for 2014!
Steffen