I would definetly try to plant it in small bunches (3-4 blades of 'grass' for each bunch). If you bunch them together in a large clump, algae would quickly spread. They creep with a rhizome, so each connected bunch should shoot off in at least one direction. If you split it up, you'll get more offshoot directions. Problem is, that they fall out of the gravel really easily, especially if you have fish that bug them (My gourami likes to rip it out and make a nest
Plant it right the first time, so it won't fall out, or you won't have to move it, as it seems to be much more sensitive to being bothered than any other plant I've messed with. Based on a post I read, and my experience, it doesn't seem like it it will bother to grow additional roots where it already has some. The new roots seem to only grow where the new shoots are, so it's a pain to anchor it, since you have to wait for new rhizome growth before it happens.
If you live in the U.S. I'd check the local walmart. I've seen what appears to be 3 or 4 different types of the hairgrass. The giant, and 3 of the smaller types. Most of the time, the offerings are crap, although occassionally, you'll find a ridiculously pristine example...
Microsword's haven't given me any luck. All the 'leaves' didn't like the high lighting I had, and quickly grew furry algae on them (algae didn't spread to anything but them). It was *very* slow for new shoots to come out, and even then, it wasn't as impressive.
Although probably not the look you are wanting to acquire, but narrow leaf chain sword seems to spread ridiculously quick, I'd give it a look if all else fails.