There is no networking code at all in the HPL2 engine, so, unfortunately multiplayer is not an option.
As for the tools.. The linux version was release recently, however the Mac version is "stuck" due to glorious bugs in Apple's outdated OpenGL implementation (a broken OpenGL 2.1 implementation vs. the lovely OpenGL 4.1 implementation on Linux box)
So until I figure out how to either workaround the bug in Apple's OpenGL or Apple updates their OpenGL (which I soo hoped they would have done with the 10.6.5 update, but they didn't) the Mac developer tools are probably not going to make their way out the door
Workaround.. You can run ALL of the developer tools inside of a windows VM in VMware fusion (probably Parallels as well). as I have tested this on Fusion 3.0 running Windows XP. It's not ideal but it works. Not sure what Vmware does that works around the issue, but they do something.
They do NOT work in wine however. Well that is not entirely correct.. they load and run in wine (ie crossover games). But since they are using the same OpenGL implementation they exhibit the same "behavior" for the "editor" tools (viewer tools work fine). This behavior is that they don't render at all unless you obscure the window (ie.. pressing F12 to have the OS X Dashboard open and then close).
Now, if anyone has an intel mac that does NOT exhibit that behavior running the HPL2 level editor via Wine I want to talk with you so I can figure this out. So far I have tested on the following cards with the same results.
Nvidia 7300
Nvidia 8800
ATI HD 2600
Nvidia 320 (mac mini)