"OCSP stapling":https://en.wikipedia.org/wiki/OCSP_stapling is used to assure a client the certificate is still valid (i.e. not revoked); you can put an OCSP response into the certificate file in an "OCSP RESPNSE"-PEM block (there is probably no standard for this, juse base64-encode the DER-response you have), or specify the (DER or PEM formatted) OCSP response as separate file using "ocsp" in a "pemfile" block.
Server Name Indication (SNI) should work fine, as an OCSP response is only used if it matches the certificate in use for the connection.
The fetch backends do NOT support OCSP stapling yet (in the future they should support the "OCSP RESPNSE"-PEM block).
Lighttpd does NOT automatically reload OCSP responses; you have to restart to load new OCSP responses (a cron job is probably the right way to do it).
If you have your certificate and the issuer-certificate (the one that signed yours) in separate files you can request an OCSP response like that (using the GnuTLS "certtool"):
certtool --ask --load-issuer issuer.pem --load-cert cert.pem --outfile ocsp.der
Converting into PEM format can be done like this:
echo "-----BEGIN OCSP RESPONSE-----"; base64 --wrap=64 ocsp.der; echo "-----END OCSP RESPONSE-----"