I've installed V845 maps before using Keygen, I now want to use V870 maps with the Auto Installer & Patcher. Can someone point me to a tutorial to guide me through this please?

If you installed maps the normal way before I would say the easiest way is to check the map thread :link:
Most maps are already available with an installer and instructions are available in the same thread.

RodA wrote:I've installed V845 maps before using Keygen, I now want to use V870 maps with the Auto Installer & Patcher. Can someone point me to a tutorial to guide me through this please?

All maps here All New Maps 870.XXXX have an autoinstaller & patcher version. Instructions are in post 1.