From what I have read you can use the globalSAN initiator. However I have not tried this. What I can say is that the iSCSI initiator they bundle their mac version of the drobo dashboard with is a pain - except if you manually force your mac to boot in 32 bit mode.
I own a drobopro, had it plugged in straight to my mac via ethernet, but moved to FW800 as that has proven to be very reliable - not so much the ethernet connection - unmounting drobos via editing video footage is really not something you want. the globalSAN ISCSI could be better and not suffer from the same problems, worth a try!
Oh and if you are using the drobopro to edit HD footage or large amounts of data, make sure it stays below 60% full, as from then on it begins to slow down, up until 90 percent where it slows to a crawl. Just a word of advice from personal experience.