$ python sqlmap.py --help | grep -i post
    --data=DATA         Data string to be sent through POST
    --safe-post=SAFE..  POST data to send to a safe URL

POST /evil.php HTTP/1.1
Host: site.com
Content-Type: multipart/form-data; boundary=-------AcunetixBoundary_XRGQBWWRUS

-------AcunetixBoundary_XRGQBWWRUS
Content-Disposition: form-data; name="act"

idx
-------AcunetixBoundary_XRGQBWWRUS
Content-Disposition: form-data; name="chk"

on
-------AcunetixBoundary_XRGQBWWRUS
Content-Disposition: form-data; name="code"

01
-------AcunetixBoundary_XRGQBWWRUS
Content-Disposition: form-data; name="fid"

*