Is it possible to disable trackpad gestures I don't want to trigger on a particular workspace?
I have virtualbox fullscreen on one of my workspaces and I'd like for mouse gestures to not trigger when I am on that workspace.
This is not a feature provided by OS X.
You have to disable unwanted gestures in System Preferences → Trackpad and then use a third-party tool to enable customized gestures.
E.g. You can use BetterTouchTool to define gestures on a per-app basis. This will allow to simply not set set any gestures for virtualbox.