All 5 stud Vxls until recently use a PCD of 110mm, but for some reason the latest models use a 112mm, so will not fit.
Also, most FWD Vxl's use a greater offset than Omega's do. Although the wheels may fit, they will sit further into the wheel arches and reducing the track of the car. This not only does look very good, it could compromise the handling characteristics of the car.
My advice would be to stick with alloys that were factory fitted to Omegas. There are many different styles to choose from, so there is something for everyone. Have a good look in the gallery section of this forum, and also at Omegas for sale on Ebay, Autotrader, etc. Decide on the style you want, and put up a 'wanted' post in the test section and ask an admin to move it to the correct section.
HTH