The problem with individual fasteners along the length of a cloth, is that ultimately it will lead to sags. Clips and Pins will damage the pile.
Lets start with the simplest method:
What you need is a clamping rug/quilt hanger.
http://www.thehangerstore.com/ I believe you can find these just about anywhere. If you are handy you could make it yourself.
Another thing you could do if you are good with a needle and know how to surface stitch (Go through one layer of material and/or snag the surface of a material), or if the rug has a thick pile; you could use a strip of denim material (jean material) and stitch it along the back along the side you will hang it from, then use a rod threaded through that. This will provide even hanging along the top length of the rug. If the rug is very heavy and or large, you could use flat iron/angle iron (Flat bar and other names:
http://www.intermet.com.tr/15-flat-bars.htm ) which comes in a wide variety of lengths and widths. Some come with holes drilled or stamped along their length. The only thing with Iron is that you need to paint it with a good metal paint to seal it and prevent rusting.
I doubt you could use a sewing machine since they tend to go through the material. The idea is to have the stitching hidden on the pile side.
The first method is good if you wish to maintain the original design of the rug However where it claps down would lead to compression on the pile which over time would leave a permanent imprint. The latter could have an affect on the value, some antique dealers are pretty picky about the condition/modification of a textile.
Another method (one used by curators) is to stretch canvas over a frame; the canvass frame would be larger, having about 2-4 inches more around the perimeter of the rug, then the rug is stretched – not to hard, and whip stitched along its perimeter into place – Most likely using a heavy gauge clear “invisible” thread.
This option provides you with the ability to use a contrasting canvass like what professional picture framers do, framing inside the frame with a matt. This works very well for say a light colored lace on a dark back ground where you desire to have the stitch work of the lace stand out. You could kick it up a notch and add a frame or even further and make a “shadow box” by having a deeper frame with a sheet of glass or Lexan or plexiglass – you do no put the glass/lexan/plexi against the cloth, it is 1-3 inches off of the cloth itself.
PS: Instead of streching canvass over a wood frame, you could use a foam panel instead, makes it a tad bit lighter.