This may already be common knowledge, and it might not be the best place to post this, but I've got a bit of a tip for anyone using the Project Q motherboard, or indeed any UEFI-enabled motherboard who wants to boot OS X into safe mode or verbose mode.
Holding shift didn't work, and neither did any of the modifier combinations that would work on an Apple machine, and since the baord doesn't rely on a software bootloader there's no way to add on any boot flags. The way round it is to boot into the UEFI shell and manually run the boot.efi bootloader (found in /System/Library/CoreServices/), adding the relevant boot flags.
1. Hit F12 after powering on to bring up the boot menu
2. Select UEFI: Built In EDK Shell
3. Find the file system with OS X installed on it. Mine is on FS1, so to get there I typed "FS1:" (no quotes) and hit enter. The way I identified it was by changing to each file system and typing "ls" to show its contents. The OS X file system will be the one with /Applications and /Library in its root, as opposed to the usual folders found in Windows
4. navigate to the correct folder by typing "cd /System/Library/CoreServices/" - capitalisation may be important if you use a case-sensitive file system.
5. Type boot.efi and add the flags you want to use to the end. A full list can be found in the link below
That's everything you need. Now you can turn on verbose mode, get into safe mode or boot into single user mode. Great if you need to troubleshoot a problem.