LFE is the ".1" in Dolby Digital and DTS surround formats and refers to the Low Frequency Channel - i.e. the bass channel for soundtracks.
As Lynx says, in order to run a Sub you realistically need to use a seperate receiver which will decode the sound and send the right information to the sub and other speakers - regardless of whether the sub is powered or passive. You
could get away with using a stereo amplifier, in which case you would connect the 2 phono's from the back of the TV to an "aux" input on the amp, and then connect the sub in between the amp and speakers using high level (speaker cable based) connections.
I'm guessingn also, that you could get away with connecting the phono's from the TV, to the line inputs on a sub and then use the subs internal xover to extract the relevant information but I can't imagine it will sound too brilliant, and it would be VERY difficult to setup.
Hmmm - just read that back and it doesn't sound particularly understandable... hope you can get the general gist... it's been a long day!!
Kelvin