To change this, you can go into your registry under key
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e972-e325-11ce-bfc1-08002be10318}\
Select your wireless adapter (mine was \0000). You can tell by the "friendly name" if you scroll through 0000, 0001, ....
There is a key "NetworkAddress" which you can change to whatever you want. I saw somewhere else that it must start with 02 in Windows 8 otherwise it won't accept it. As an example, I used 020E057CD83C.
Disable then enable your network adapter and you should be in business.
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{4d36e972-e325-11ce-bfc1-08002be10318}\0000]
"NetworkAddress"="020E057CD83C"
SMAC v2.7 tool works too but is not free and all it does is change this regkey for you...