You have a lot of options there. To create linear loading you need wires or conductors folded over each other, this is typically done to get more wire, inductance, and radiation resistance for a given amount of space the antenna can occupy. What chrismo said regarding canceling out rf due to the pairs being twisted together is correct to a degree, and if it hinders performance you can violate the pair and solder say a yellow white not to the other yellow white but say to brown white. You get the idea.
See here;
http://download.prgm.org/ham/ant/linearloaded7mhz.pdfSee how he's taking ladder line and folding it back to get more wire in the air? That's what you're doing. To eliminate any reduction in performance due to cancellation from twisted pairing, wich is what twisted pairs are intended to do, solder each color coded pair together as chrismo suggested, then solder each soldered pair to only one soldered pair at the other end, each soldered in series until you have no more pairs, then terminate and insulate the ends as desired. For vlf work you might go ahead and solder each color coded wire to its mate at one end only and feed the pairs in series, making for longest length of wire and ignoring any cancellation.
The resonance points will depend upon the length of the total wire, inductance, stray capacitance, and so on and so forth, but for ambc and lf/vlf it should work dandy, and be very good at hf. If you terminate it in a variable resistor at the far end from the shack you've made a Beveridge antenna and can fine tune it for directivity - it will send to ground signals coming from the end opposite to the resistor. I suspect 400 to 1k ohms variable range will do and this will change due to moisture content of the soil but not by a large extent, once you find the sweet spot in resistance ie the stations at the back end of the antenna (away from the resistor) are markedly lowered in power, swap the variable - after you measure its value and find the closest aproximate fixed value resistor - for a fixed resistor for outdoors durability, you might want a 2 watt resistor as some find their get popped by nearby lightning strikes often if a lower wattage resistor is used. You can get tricky and place a cds cell (in the same range as the variable resistor) in place of the resistor and it'll allow for omnidirectional coverage when sunlight hits it, rather than as a Beveridge. This Beveridge antenna system provides for very wide bandwidth of reception (technically this is an aperiodic antenna, meaning it should have no peaks or nulls in response to rf energy intercepted) and if the far end is directly away from the home it should also do much in the way of reducing or eliminating rf noise coming from the home. A note should be added here - linear loading may interfere with the classic Beveridge directivity as the antenna wires are run back and forth over the length of the installation rather than a single wire, you can break new ground in a very old antenna design!
A "long wire" antenna typically is at least 1 wavelength at the intended freq of operation and will be a high impedance antenna, pretty much anything other than quarter wavelength and multiples thereof will be higher z than our rigs want to see unless they have hi z inputs. Any halfwave antenna will be around 2k ohms at the ends but around 300 to 75 in the middle and of course everything is frequency dependant. So having a balun or other means to match the hi z of the antenna will provide for the most efficient transfer of energy, if the antenna sees a low z input it will swamp the energy.
Here's a loaded vertical;
http://www.qsl.net/pa3hbb/ll.htmA friend runs this page and it's chock full of antennae and HAM radio hijinks with emphasis upon Beveridges;
http://www.w0btu.com/