For info on crucifixion in the Greco-ROman period, see now G. O'Collins,
"Crucifixion," _Anchor Bible Dictionary_, ed. D. N. Freedman, vol. 1, pp.
1207-10, which includes a short bibliog. of helpful material, including
ref. to the lst-cent crucified man found at Giv'at ha-Mivtar, which is
very helpful for seeing how it was done. E.g., the man had been nailed to
a cross of some sort, the nails put through his wrists and feet.
Larry Hurtado, Religion, Univ. of Manitoba