Think of "shotgunning" like you would "mono-blocking". Just as you have one amp for each channel, you would have one cable for each polarity of the speaker jacks. This would mean using one conductor ( solid, stranded, braided, etc.. ) in it's own jacket for the positive and another identical yet separate cable for the negative. Cables that share both polarities within one common jacket can not be shotgunned unless the following approach is taken.
A somewhat common method of "shotgunning" is done with Kimber 8TC. The 8TC has 8 blue conductors and 8 black jackets in each braided run. Most folks end up using the 8 blue jacketed wires for the positive and the 8 black wires for the negative. In order to "shotgun" this cable, one would tie the black and blue jacketed wires together and use all 16 of the conductors for one polarity of the speaker. Let's say we did the positive. It would now require an identical cable i.e. 8TC using all 16 of the black and blue jacketed cables to connect to the negative polarity. You would literally have two seperate "barrels" of 8TC to make up one full run on a channel. In order to do this on a 2 speaker system, you would literally need four complete identical runs of 8TC to "shotgun" the cables for both channels.
This approach is obviously more costly and effectively doubles the gauge of wire being used. It also changes ALL of the electrical characteristics of the cable being used. Due to the physically separate runs for each polarity, the "low inductance design" of the Kimber's is now completely negated and the design now becomes high inductance. The same thing can be achieved by simply "unzipping" zip cord and spacing out the two conductors. Obviously, the type of conductors used ( individually insulated for the Kimber vs the lumped together strands of the "zip" ) would still create a slightly different electrical characteristic.
In order to "shotgun bi-wire" a stereo system, you would need EIGHT runs of 8TC. Let's start with the right speaker. One positive for the woofer, one negative for the woofer, one positive for the tweeter, one negative for the tweeter. You would then have to duplicate that same set-up for the other ( left ) speaker. Now you are talking TALL cash.
In terms of "bi-wiring", my PERSONAL take on this is that each section of a speaker ( woofer and tweeter on two way, woofer, mid, tweeter on three way, etc... ) each has it's own separate positive and negative wires feeding it. In other words, you would need four wires insulated from each other to "bi-wire" one speaker, eight wires to do a stereo pair. In this sense, Goertz MI-2 Veracity is technically not really "bi-wired" so much as it is "bi-terminated". Since this design shares the same conductors for each frequency range, you can't "bi-wire" with Goertz unless you literally have a seperate cable for each frequency range ( highs and lows ). The main advantage to "bi-terminating" the Goertz is that this allows you to bypass the factory installed jumpers.
Another version that is also called "shotgun biriwing" can be done this way. A run of Kimber 8TC is used for the woofer and a run of 4TC is run for the tweeter. While these cables are obviously separated from each other to connect to the various woofer and tweeter jacks on the speaker, they are sometimes connected to the amplifiers binding post using one common spade or banana jack. These cables are still "shotgunned" as the highs are physically separated yet maintain a common connection at the amp. It is kind of confusing as the polarities are not separated to form the "two barrels" in this version of shotgunning. Rather than that, the highs / lows are physically separated i.e. making the "two barrels" of the "shotgun" terminology.
Some cables have multiple wires all individually insulated within one bigger jacket. Some of the more common brands that do this are Audioquest, Straightwire, Axon, etc... Using this type of cable or even something like Kimber, XLO, etc... you could separate individual insulated runs out of the bunch and divide the signal WITHIN the cable itself between the highs and the lows. This is called an "internally biwired" cable. The Goertz MI-2 Python's can be done in this manner also, as they use four conductors per jacket rather than the two conductors that the Veracity uses. While this approach may give you some benefits, it is reported that physically separate cables between the highs and lows work better.
This can be a VERY confusing thing to try and explain. Besides being tired, i'll let someone else try to confuse you with their explanations : ) Sean