For this particular application you do not really need CAT5 cable. Actually, I would not recommend using CAT5 wire at all since it's more tightly twisted than CAT3, and therefore the effective length of the conductor will be more than that of CAT3. CAT5 performance is not going to be maintained over the 1400FT distance anyway.
However, to splice either CAT5 or CAT3 for this particular application (not the real CAT5, which is not allowed to be spliced at all) you can use 2-wire splices like those "Scotchlok" ones by 3M. If it's going to be outdoors, you may want to pick up the gell-filled ones at Home Depot near you.
Dmitri Abaimov, RCDD