Check out my flash FAQ for more details about your options:
http://www.the-meissners.org/olympus-flash.html
Your site says the Digi-slave DSF-1 is a slave only flash but
olympus has a ttl-pc cable for the c-3040z and the DSF-1 says it
can be used with a hot shoe.
If I get a "cold" shoe that becomes "hot" when connected to a PC
cable and mount it on a bracket will that work?
I'm not familiar with any of the stuff I just said/asked so don't
flame me
Yeah, it should work, if you want a flash that can be used as both
a slave and a generic non-TTL flash. You could also buy a Vivitar
283 and Wein digital slave peanut for the same amount as you would
spend on the DS-1 and pc-sync to hot-shoe converter, which might
give you more power. I need to update the site, the DS-20 from
Sunpak that Ritz sells for $29.95 (guide 59 feet at ISO 100, which
is roughly 20-25 feet in automatic mode) is also an option if you
don't need the power of the DS-1 (guide 79 feet at ISO 100, roughly
30-45 feet in automatic mode). FWIW, a guide of 79 might not be
powerful enough if you are going to bounce the flash off of a
ceiling or wall, unless your subjects are fairly close.