Icon Preview Settings

I need to have a pixel preview of my icon in a certain size: the exact size of the icon canvas (in this case 56 x 56 px). What is the easiest way to get a preview in this size? The manual explaines only a way to change the settings for the Inkscape Icon Preview in Linux on my computer. I work with Windows and I hope that there still is an easier way than to go into the generall Inkscape preferences.

This is the description from the manual:
Which sizes are displayed can be specified in the preferences file (Linux: ~/.config/inkscape/preferences.xml) under the iconpreview group.