[exim] Operating on different spool directories

I am in the process of setting up exim and I am considering using
MailScanner for spam/virus filtering. Use of MailScanner dictates that
exim run two daemons, one for listening on port 25 and another to do
qeueu runs. There are two different spool directories in this setup, one
for incoming messages, the contents of which are to be picked up by
MailScanner for spam/virus processing, and another one for the messages
post Mailscanner processing.

My question is this: Can I control which qeueu a command operates on? If
I call exim3 -bp for example, can specify which qeueu it should operate on?

Thanks,

Mordur Ingolfsson