I believe you can set environment variables based on apache config
directives, for this I'll point you to the apache docs and wave my
hands. Start with mod_env, I think the examples there are helpful.
For my customers, I pass the X-Forwarded-Proto header, and provide them
instructions on hooking their sites up to that.
My suggestion is tangential - log via syslog, and then do your rotation
against syslog, not pound. This way you don't have to restart pound,
and you don't interrupt web traffic flow.
I don't use it. I thought it was somewhat unstable in the past, and I
don't really need it.