this is a skeptic to me. how are you going to inject signal from a finite impedance source into almost zero impedance high powered line (mains)? let alone the noise sachejj mentioned. i will not bother to answer even i'm an expert. OP did not give complete description imho.
The two protocols mentioned have two things going for them: slow bit rate and know position in the existing wave to send or receive (minimizing the noise issue.)
For example, the X10 uses a 1 ms 120 kHz burst at zero crossing for 1 and lack of a burst for zero. This allows you to filter out noise by using a band pass on 120 kHz. This also filters out the mains frequency. However, with only at zero crossing, you have 120 Hz or 100 Hz bit speed. Less with collision and error correction. Injecting the signal isn't an issue, because you are only using the power lines like a transmission line. The frequency burst doesn't have to be 115-230 V. It just exists on the same line.
Universal Powerline Bus uses a voltage spike at 1 of 4 known positions in a half cycle, rather than just the zero crossing. This allows values of 0-3 (2 bits) in each half cycle. So you get double the bandwidth of X10, 240 Hz or 200 Hz. The voltage spike is usually created by dumping a capacitor into the line at the right time.