Hi Rado,
Please see attached screen snaps....
I think that's about what you want.
Forgive me on the sizes. Millimeters baffle me. I tried!  

The trick is to use a template for the print size, and then (in freehand mode), add your actual image at the size print you want, crop off,  drag one over the other.
The image will end up below the template, but go into the page editor screen and click in the center of the template.
We are in the page editor screen because it is easier to see the next step.

By clicking , you are selecting. The template or the image. When you have the image selected, you will see dots where the 4 corners are located.
Right click and select MOVE TO FRONT.
Now turn on crop markers.

It sounds harder to do than it really is. (Under a minute)

Let us know if you need more clarification.
Sorry for the delay
Fred
PS. Terry just reminded me that you can also do this using a Mat (in white) instead of a template.

Not 100% sure of what the placement is, and if one print per page or not,......
You can put all your images in the queue.
Then select all from the right click menu, then Right click menu again and slick on make a mat (grow mat).
Select the size as if it was the actual print size perimeter, and all the images will have a mat applied.
Then Print

The images I want to print all have different aspect ratios (which I want to keep). You can reproduce my screenshots with these two dummy black images I've used to make it myself.

https://dl.dropboxusercontent.com/u/150158/square.png
https://dl.dropboxusercontent.com/u/150158/long.png

1) set the page size to A4 landscape
2) set the print size to 140x180mm with 10mm border B, auto crop off
3) add square.png
4) add long.png
5) positioning template/centered
6) show guide lines

What I'm trying to achieve:
1) I have 40+ images I want to print
2) I want to print 2 images per A4 sheet
3) I want to cut the sheets and each piece of the cut paper should have the dimensions of 140x180mm
4) each print inside that piece of paper should have at least 10mm border and keep its aspect ratio (so the maximal printable area on each cut is 120x160mm, the square image for example would be 120x120mm)
5) each image should be centered on the cut

Qimage already computes the layout the way I want it, I just need the cropmarks for the 140x180 size so that I can cut the sheets.

I can confirm that the crop marks for my case are now displayed correctly in v114. Thank you for the prompt resolution and happy holidays everyone.

Rado