Ok, my axio has 4 velcro straps (one at each corner per se).
Starting with the rear, I found the easiest way was to wrap it under the rear light etc. I wrapped it then cut the straps to get a better fit. Then heated the end of the straps so they would not fray. This method allows the bag to be really sinched down tight and doesn't cover the light from the rear. I did it this way to help when the bag is installed (more later)
For the front straps, these go under the seat and wrap to a piece of industrial grade double sided velco (its actually sticky single sided I stuck together, one side hook, the other side loop) Make sure its x 2 width of the straps!!
You simply wrap the front straps around the velcro piece and slide over the seat (you need to play with it to get it to fit). So when its on the bike, its secure.
To install, unlock the seat (remove if necessary), slide the bag over the seat and ensure the front straps are tight enough around the seat and velco piece to ensure its sinched down. push the seat into position.With the rear of the bag still free you get access to push the seat to lock in position (assuming original lock etc). Then you sinch the rear straps as described above.
To remove: undo rear straps, unlock seat, slide back back over seat. relock seat. easy.
WIDTH example
One strap wrapped
Two straps wrapped
I done this on my Triumph Tiger and Hypermotard and now on the Strada. Even if it doesn'twork for you, it will give you some ideas of how to maybe acheive the "strapless"look".
Good luck
