Lap siding is recommended to overlap by 1 1/4 inches. After being pointed in the direction of a Fine Homebuilding article ( Thank You Woodswalker) I've discovered there are a variety of tools to allow easy accurate spacing of the overlap.
(http://ecx.images-amazon.com/images/I/41Z6DK9NBBL._SL500_AA280_.jpg)
Many tools available from amazon.com
This should work, or search "siding gauge"
http://www.amazon.com/s/ref=nb_ss_gw?url=search-alias%3Daps&field-keywords=siding+gauge&x=0&y=0
Shears for fiber cement. Add this to an electric drill, 18 volt cordless would work.... $107
(http://ecx.images-amazon.com/images/I/4149Q7FBTEL._SL500_AA280_.jpg)
http://www.amazon.com/gp/product/B0009MFX7O/ref=s9sims_c2_60_at2-rfc_g1?pf_rd_m=ATVPDKIKX0DER&pf_rd_s=center-2&pf_rd_r=1T1XJHAWM58PG5W1YR24&pf_rd_t=101&pf_rd_p=320448701&pf_rd_i=507846
The hanger I used was adjustable in 1/16th in increments, sure came in handy when hanging siding with one person, the widths of the siding are not very consistant. Google solo sider.
w* to the forum, jr1318.
The gauge the pros use on the commercial jobs here they make from wood and it measures from straight bottom to straight bottom of the siding allowing the crooked edges everyone mentions to be mostly on the top.
Found the pix.
(https://i35.photobucket.com/albums/d184/glennkangiser/P1000574.jpg)
(https://i35.photobucket.com/albums/d184/glennkangiser/P1000575.jpg)
The old discussion
http://countryplans.com/smf/index.php?topic=1887