Those are both great plants, Hwom. Dwarf hairgrass will need medium lighting while dwarf baby tears does better with high lighting. Both can be grown in the med-high ranges. If the lighting is too low, growth will get real sparse and leggy. A nutrient rich substrate is best too. Under decent conditions, both plants will spread around nicely.
Standard aquarium lighting or areas that are shaded a lot from above aren't going to cut it really for either of them. So you'll have to have upgraded your lights ahead of time (if you haven't already).
Edit: Figured I'd add this video so you can see how to plant these if you decide to get some. Watch for that segment at around the 5-min mark.
I have moderate light, right around 2.3 WPG, and both plants grew fine for me. The thing that ultimately made me rip them both out was a sand substrate and cories. Cories just LOVE to rip this stuff up constantly. If you have cories, I would recommend a substrate like flourite or small gravel, nothing to large, and not sand.
small gravel will work with the dwarf HG, but I'm really not sure with the baby tears. They have TINY roots and I think you'd have trouble getting them to stay down. As long as you don't have fish that love to play in sand, it really would be the best choice for this.
Good to know that one should "mow" the hair grass prior to planting and leave 1 cm of rock wool on the HC when planting. Also, planting in a dry aquarium is more easy by far than planting in one that is full or even partially full.
Both of these plants will grow much more quickly if you start them out in a dry aquarium and give them a few weeks to grow emersed (not underwater) before filling the aquarium up with water. Also, then you won't have to deal with CO2 or algae.