dude it works on 6 just fine.. But if you install the native tools and use vmx3 pfsense is not going to work unless you disable csumming at with ifconfig vmx? -rxcsum -txcsum -tso4 and this has to be done every boot.
Just install the openvm tools package in pfsense there you go done.
I can tell you for fact that these instructions work on getting the tools installed
http://www.v-front.de/2015/01/pfsense-22-was-released-how-to-install.html
This works on esxi 6, have done it many times on many different vms of psense.. But again if your wanting to use vmx3 nic in pfsense doing so will break pfsense from passing traffic.