I just loaded dwarf hairgrass into my 10 gallon as well. I'm using a gallon size bottle to create CO2. It's costing me about 30 cents a batch, i bought a cheap effective diffuser for 9.50. I use 4 cups sugar, 1 teaspoon of yeast and 1 teaspoon of baking soda, lasts about a week.
My lighting is 2.25 watts per gallon and I haven't used any form of fertilizer (YET!). The tank is shared by wisteria, anubias nana, and a moss ball, all of whom are rated for the low-light conditions.
Essentially I'm posting to say, you're not the only one making it happen, and I'll let you know how long it takes for this grass to propagate, if ever. I did separate my very similarly sized patch into about five different patches. My tactic is to let it chill out, get acclimated and keep it's color for about two, maybe three weeks. Hopefully it tries to grow taller, which I hear is a common effect of the low-light setup, at which point I'll trim it way down, which I hear causes the grass to grow runners.