>I hadn.FN"t really thought of making it executable$B!D(B I think thereN"s a
>magic cookie at the beginning of a ZIP file so a hashbang might not
>work if the archive were intended to be spec-compliant.
No, the magic cookie (PK\005\006) is at the _end_. The central
directory and file entries also have magic cookies (PK\001\002 and
PK\003\004 respectively), but those don't have to be at any specific
position but are pointed out as file offsets rooted in the PK\005\006
header at offset file_size-22.
AFAICR it was standard practice to make self-extracting ZIP:s on
MS-DOS by just cramming an MZ binary before the archive (and adjusting
the offsets accordingly).
It should be pretty easy to just put something at the start if
creating the archive by hand like Filesystem.Zip is doing.