The clutch should not be damaged, but may be contaminated with brake fluid.
If it were me, I'd investigate why the slave cylinder was leaking by removing and inspecting it. My first thought is that the pressure popped the front of it off because it was not engaging the clutch release arm correctly
. That is pure speculation as I have never taken a Boxster clutch slave apart, but I have taken plenty of other slave cylinders apart and it would be true for them. If true, you have brake fluid and possibly parts in the bell housing, as well as a mis-installed clutch release arm, meaning the clutch needs to be removed and re-installed.
Or
The slave cylinder seal happened to spring a huge leak and was ready to go anyway. In that case the front of the slave cylinder is not popped off, and you need to fix the sealing problem only. You still face possible contamination of the clutch disk, and running it that way will damage the clutch, which leaves two options:
1) Put it back together with the seal fixed, and see how the clutch feels. It will likely be grabby and even stink if contaminated - that means pull it all apart and clean everything with brake cleaner. Running for anything more than just getting the first indication the clutch is contaminated will damage the clutch.
2) Strike first by pulling it all apart and cleaning everything with brake cleaner to know everything is correct.
With a new clutch I'd go with #2, with and old clutch I'd go with #1.
I don't think that trying to clean it while assembled would be effective at all, meaning spraying brake cleaner in to the bell housing - that could take lubricant out of the bearing as well.
I've not removed a slave cylinder with the engine installed, but it would be tight! Good luck and keep us posted!