There are currently only firmware updater tools available for Windows and Linux. I believe that an aspiration to develop an OSX updater tool was expressed when Mac support debuted in SDK 2.0, though there is no information about when it might be released.
If you do not have access to a Windows or Linux PC to run the updater tool, an option I have speculated on in the past might be to use OSX Bootcamp to run Windows applications on a Mac.
Another option would be to purchase an Up Board single-board computer from Intel's online Click store and run the Linux updater through that.
I have no knowledge about whether the Linux updater tool would work with VirtualBox. Librealsense do recommend against using VirtualBox though.
"Due to the USB 3.0 translation layer between native hardware and virtual machine, the librealsense team does not support installation in a VM . If you do choose to try it, we recommend using VMware Workstation Player, and not Oracle VirtualBox for proper emulation of the USB3 controller".