PGP sign mail without MIME

[Lukas Ruf]

Dear all,

in muttrc, I easily can set a sendhook such that every email gets
signed by PGP.  But this always sets the MIME type accordingly.

Is it possible to have a sendhook defintion that allows the 
 PGP sign mail without MIME 
as I can specify it manually with ctrl-P in the send menu?

Thanks for any reply.

Lukas
PS: In the FAQ, I could not find the answer.  Therefore, I am asking
    here.
--
Lukas Ruf                        Swiss Federal Institute of Technology
Office: ETZ-G61.2                             Computer Engineering and
Phone: +41/1/632 7312                        Networks Laboratory (TIK)
Fax:   +41/1/632 1035                                      ETH Zentrum
PGP 2.6: ID D20BA2ED;                                    Gloriastr. 35
Fingerprint 6323 B9BC 9C8E 6563  B477 BADD FEA6 E6B7    CH-8092 Zurich