The Janome cloth guide doesn't have a screw - it attaches to the embroidery unit.
The screws I was talking about are those you may have if you have bought any other screw attached Janome attachments such as the circular sewing guide or binder. Or you can purchase an additional presser foot screw since the hole in the bed is the same size - try your foot screw to see how it fits. Though when you purchase the Singer seam guide that usually comes with a screw anyway which should fit, but do check as you don't want to ruin the screw hole in your needle plate.
The guide slides left and right to whatever distance away from the needle you need. When you have it where you want it you just tighten the screw down. It doesn't of course give you as many options and distance from the needle as the cloth guide.
In order to set it I put a quilting ruller under the presser foot and check to see that the needle will drop on the mark that will give me the seam width I want - so if I want a 1 inch seam I set the ruler under the foot with the needle touching the 1 in mark from the edge of the ruler - put the presser foot down to hold the ruler firmly in place - butt the seam guide hard up to the side of the ruler and tighten the screw and then remove the ruler.
You can also angle the Singer guide diagonally so you have a point to feed the fabric too when you are going round a curve
I think the new Janome guide foot will be useful for when you want to sew several rows of stitching next to each other and keep them straight without having to mark the fabric - you can't do that with the Singer guide. - I think it would be more accurate than using a quilting guide bar.
"Live like someone left the gate open". Kimberly Burnham