Best thing to do, take the spedo off, then unclip the dials wiht the milage on it, then do the same wiht the old dials and just swap em over.
Regarding spedo cable, you have a metal bit behind the pannel, if u get the edge of it on there then you can take ur hand out and just push, just give it a tug to make sure its fixed on, prob solved.
Got and installed mine2day btw, only got a few cuyts while trying to get my hand behind to undo spedo cable.
All works cept fog light thing, but can live wihtout that, dunno if tem guage works yet, only been 5 mins done the road....after shreading my torx bit sticking the dash on.
They look the dogs b0ll0x!!