How long can my MacBook Pro sustain greater than 100% CPU usage?
The thing is that 100% CPU usage refers to a single one of the cores in your CPU being fully loaded (or an equivalent load distributed among all the cores). I assume your MacBook Pro has a dual core CPU with HyperThreading; that's 2 physical cores plus 2 logical cores exposed by HyperThreading. Thus, you could in theory achieve as high as 400% CPU usage (4 cores times 100% each).

As to whether it is sustainable, in principle it should be, if the cooling system is in order and the cooling vents are not clogged with dust or blocked by any objects. Even if it's not and you reach supposedly dangerous temperatures, the CPU should throttle itself to prevent any damage.