If you are only going to shoot a couple of products then shoot it on any neutral background and send it to an external masking service. They are really cheap, quick and the result is perfect. bright-river.com is just one of dozens of services.
If you refuse to pay anyone else for masking, or refuse to do the masking your self, you must face the fact that you need the background to be back lit. There is no other solution.
The answer to "how" depends on your budget, and the budget depends on the physical size you need.
If your objects are small (like shoes, scarfs, gloves etc), you can just use a tilted softbox as your backdrop and place the product on the diffusion panel. Light the product from above with another flash. Boom. Done. Happy life.
It's not the most beautiful solution, but it works for lighter stuff. Heavier products will of course sink down and you will have light coming from the sides on the product and make everything look like shit. Then you need to separate the product from the background by using something transparent like a sheet of glass/glass table/front of a glass fridge (done that, been there). You won't even have to worry about reflections since the background will be to bright.
This is a very "quick and dirty" solution, and that goes hand in hand with the budget. Cheap = dirty. The free lunch still isn't free.
The main problem you will encounter is that you need to blow out the background to get all the softbox wrinkles and un-even lighting to become evenly white. And when "blowing out" stuff, you WILL have quality issues:
Light straight into the camera lens can lower your contrast and make your product look a washed out. This is much due to the quality of glass in your lens, so if this is cheap - this might be a problem. If the contrast-issues are mild, this can be easily solved in your raw-converter/photoshop, but this takes time and require some software skills.
The edges of your products will not be super detailed, crisp and sharp due to the over exposure that will make thin edge details to disappear.
The sides of your product facing outward will suffer from over exposed rim lights. This is due to a physical fact called the Fresnel-effect where light will reflect onto your product, and this reflection will be 100% the same brightness as your background = over exposed = no details.
So, what to do to get a more professional look?
You need to put the hand in your pocket, bring out the cash and buy a milky white plexi board.
Then you need to light this EVENLY from behind. A softbox is perfect. If the plexi needs to be bigger than your softbox, you need to build some kind of stand for the plexi so it can be floating above the softbox. The bigger the plexi, the bigger the distance, the higher you need your camera to be. And this is the next challenge - how can you get your camera to these heights needed?
If you use a wide angle lens, you save height but loose in a correct perspective. I would say that 50mm is the acceptable limit for what a pair of trousers can take. Wider than that will cause perspective funkyness. 85mm/100mm/120mm is an optimal focal length for a professional looking perspective when shooting from above, but demands a high camera stand.
A cheap solution is to mount the camera on a A-ladder.
You would most probably want to shoot teathered to a computer so you don't need to run up and down the ladder. You are going to spend most time styling your clothes, and you want to see how it looks in camera ALL the time. What you are seeing with your own eyes have nothing to do with the final image (you are to close to percieve the right perspective, and the strobes are of course creating shadows you cannot see with your eyes).