I assume you are trying to hook up subs? I am 99% sure you have no A/V hookups (i assume you are talking about RCA outputs?, and the factory deck? CD?) It isn't easy dealing with the Bose system while adding speakers... The autmotive stereo industry operates at a 4 ohm standard... Bose opted for 1 ohm...
(the less ohms the less quality, but the less power needed to make a ton of noise--- home stereos are 6 or 8 ohms, higher because there are no space constrictions and the sound is cleaner)
It is possible to wire in subs from the back speakers, but it must be done before the bose amp, then with a crossover... Typically you have to do a wire to RCA conversion, to an amp, then back to wire again... sound quality usually gets worse through a converter though... If you are still interested, write back and i will give some more details