As you heard, We have done this in the past With some problems learned, First of all you need a hardware device such as a FireCracker Computer Interface, You can purchase one from Here
http://www.x10.com/automation/firecracker.htm For only $39.99
Here is a software for that interface after you will need after purchasing
ftp://ftp.x10.com/pub/applications/firecracker/ck18a.exe The interface sends commands to the link module, which translates the wireless signal into an X10 signal.
Interfacing Hal would being the next up in creating voice commands for ultra Hal, What I use for voice commands is a software I use called E speaking,
Which is Great for controlling lights off and on, stereos, T V's, Opening trunk, Starting up your car to warm it up in the winter, the only thing that is required windows like a laptop for testers, desktops for novelist, or in -car computers running windows.