This is a reminder for future Ricardo, as it was the 2nd time I searched for the information. After this configuration, Virtual Machines connected to this virtual switch will be able to access the Internet (not only) connection of the host.
New-VMSwitch -SwitchName "SwitchName" -SwitchType Internal New-NetIPAddress -IPAddress <NAT Gateway IP> -PrefixLength <NAT Subnet Prefix Length> -InterfaceIndex <ifIndex> New-NetNat -Name nat -InternalIPInterfaceAddressPrefix <NAT Gateway IP Network>/<NAT Subnet Prefix Length>
Also, the following is a quick and dirty way to get the Hyper-V switch interface index required above.
(Get-NetAdapter -InterfaceDescription Hyper-V*).ifIndex
Hope this helps.