I've never bothered when travelling, largely because my (soft) camera bags are far from airtight, and the bag is opened and closed so often it becomes pointless. It might be worth it if you're away for months, but if it's just a matter of weeks, I wouldn't bother.
If you use airtight cases (e.g. Pelicans), it might make some sense, if you aren't using the camera gear for a day or more at a time.
I guess one of the concerns is keeping the silica gel out of contact with your gear, esp the fine dust particles. So you want to put it in a porous bag (fabric?), but that would lower it's rate of moisture absorption drastically.
Offhand, if you need to store your gear for a day or two when abroad, perhaps an airtight container (even a large Ziploc bag) with silica gel in an open container off to one side. You can't jostle or move this around too much without spilling the gel and exposing your gear to the dust though.