Upgrade to v6.4, and make a supout.rif file with the card inside. Then send to email@example.com
Maybe we can add support
For any one interested I did manage to get the Huawei EM820U working.
It was really simple when I realised that this card required a ppp connection and not a DHCP client like the MC7710!
Set ppp-out1 to use USB2, data channel 0, info channel 2 and APN three.co.uk (in my case, for three in the UK)
You will also need to add a NAT rule. chain: srcnat, out interface: ppp-out1 action: masquerade
Then you're all good to go