Yubico PIV Tool is available for OS X and Windows as well:
https://developers.yubico.com/yubico-piv-tool/Releases/The difference is that you don't install it, you use Terminal (OS X) or Command Prompt (Windows), change directory to the folder's bin directory, and run the commands from there.
The PIV applet can also be reset from YubiKey PIV Manager (Manage device PINs) - lock out the PIN and PUK (this is already locked if you used the default options when initializing the applet with YubiKey PIV Manager), and then reset.