I presume we are talking the "home" type steam cleaner and not the industrial buggers.
I've not done the Zeds bay (I actually jet washed it this time because my steam cleaner broke) but I've done previous cars with no problems at all.
Personally I follow these rules.
Bag up anything that looks like trouble (IE Alarm sirens, Air filters if exposed etc etc)
dont douse water into any intake pipe/tract
dont spend half an hour rinsing for rinsing's sake.
With regards to the steam cleaning, Its actually pretty good because you use less water than jet washing and its also hot so great for cleaning out grime. I found it particularly good at cleaning electrical connectors although again you have to proceed with caution.
and if you can, always finish by blowing out with a compressed air gun, it minimises the problem of water sitting in places it shouldnt.
Once done, get the engine up to temperature to evaporate anything remaining and make sure everything is functioning ok.