OCSP stapling via web proxy

Hi,

I'm trying to set up OCSP stapling but our firewall currently does not allow outbound port 80 unless its via a squid proxy server. OCSP stapling requests are ignoring the OS (Centos) proxy setting. Is there a way to tell NGINX to get its OCSP things via the proxy, or is the only way out to open up the firewall to the OCSP servers?

NGINX 1.6.0
Centos 6.4

Thanks.