you could get a cheap mixing board("behringer" anyone?), plug 4 mics into the lexicon, then the other mics into the mixer, and run the stereo out of that into the stereo input on the lexicon(i THINK i recall that there is one stereo RCA in)
so now you can use the mixer for saaaaay, overheads, or whichever you choose, you could pan one hard left and one hard right, andthere ya go... 6 mics into 4 inputs...or ever more depending on how man inputs there are on the mixer...the only downside is youll only be able to process the stereo mix from this, unless you only use to mics in the mixer allowing you to process each individually as a left and right, which you could make into their own track after recording