Try 4 hours. Argh!!!! What a day. Ordered myself a new Renthal R3 O-Ring chain and a rear Paddock stand last week and my mate came on Saturday to help me fit it. So, first things first tried to get the old chain off, couldn't get any of the links to break, so had to borrow my neighbours angle grinder. Got chain off, cleaned up rear sprocket and other bits and pieces, attached new chain to old one, pulled through over front sprocket, everything going nicely. Got it over rear sprocket and stuck the link pin through, O-Rings all in place and put the plate on the front, then began the process of squeezing it on. Had 2 little metal things though, looked like curved (E) shaped things. Couldn't for the life of us figure out what they were for. So hours later after getting my Neighbour to even help out we realise they're to go between the plates on either side of the link so that when pressing the link on you don't squash the rubber O-Ring seals. Although at what point do we realise this, after we've got the plate squeezed on and one or 2 of the O-Rings are sticking out a bit. Managed to get the Plate riveted on ok, but I'm concerned now about how good the seal will be. I'm going to keep checking the O-Rings to see if after riding it a bit I'll be able to push them in a bit more. Typical, but I guess this is one of those cases where you live and you learn. So I'll probably end up replacing the chain again whenever I need to replace the Sprockets, argh!!! So annoyed. But like I said, it's all a learning process and I've learnt the hard way how a chain should be replaced.

Does anyone know if it's dangerous to be riding with the chain with 1 or 2 of the O-Rings's squashed a bit on the link pin? Will I be able to push them back in, or will it be alright so long as I keep the chain well oiled?

I think your best bet is to get a new soft link and fit that.
When I fitted mine I first measured the distance between one of the links so as to make sure I got the distance right in order to make sure I did not nip and squeeze the o-rings.
Once you have squeezed the side plate on its practically impossible to ease it back if you have nipped the o-rings .

Hey SuperJack, yeah i was wondering about trying to just get a new soft link and then replace it. Hoping it'll be alright for a bit though until I get a chance to get round to it, got a busy month ahead of me.

I would replace it sooner rather than later reason being if you have nipped it up enough to have pushed the o-rings out the chain link is obviously too tight and therefore creating friction friction causes heat and the link may fail.
If it does let go consequences could be painful.
Replace now is my advice