How do you register for an OUI vendor prefix for MAC addresses?
There are lookups such as this offering: http://www.adminsub.net/mac-address-finder/microchip
I want my own AA:BB:CC prefix.
https://en.wikipedia.org/wiki/Organizationally_unique_identifier
OUIs are purchased from the IEEE Registration Authority (as the 2nd paragraph of that Wikipedia article says).
Note that there are three MAC prefix registries now, since it turns out there might not be enough OUIs for everyone. If you need the 24-bit OUI specifically (e.g. for network protocols which use it as a vendor identifier), those are now labelled MAC Address Block – Large and cost US $2,655 to register publicly.
If all you need is a unique MAC address prefix, IEEE also has 28-bit ("Medium") and 36-bit ("Small") MAC Address Blocks, for $1,595 and $665 respectively. A "medium" block has 20 local bits remaining, for 1048576 unique devices, while "small" only has 12 bits for 4096 devices.
For personal use you can generate random MAC addresses yourself, as long as they have the "locally administered" bit set (mac[0] |= 0x02) and the "multicast" bit unset (mac[0] &= ~0x01).
