Brake Caliper seal problem

Last night I replaced the pistons in one of the front calipers on my 110. All the rubber seals went in smoothly but when I got to the metal retaining seals I managed to bend 3 of the 4 trying to get them in.
They are of course now useless and I'll have to get some more, but is there a special way or tool to do this?
There is no mention in the Haynes book of lies or the Landy Workshop manual I have read.

Put the fluid seal in first, then the piston, leaving it about 8mm proud, to guide the wiper seal / retaining ring. Fit the wiper seal into the retaining ring first (bit fiddly), then slide them down over the piston and ease them into place as best you can with your fingers. They then need tapping gently and evenly into place the last few mm. I used an old wooden ruler and a tiny hammer to do that, working my way around and around the seal a tiny bit at a time.
Lubricate everything with clean DOT4 brake fluid (NOT DOT5) to make it easier.
I did mine off the car / on the bench, which I guess, is a lot easier than on the

Yeah there is no easy way of doing the dust seals, they can be gits. Not helped by poor quality either, I had some out of the same box that were all slightly different. Great!

Cheers Trewy, we basically tried that last night and failed. I think I'll pop the caliper over to Safari engineering and get them to fit some new ones.

Make sure the recess for the retaining ring is very clean.

As has been said above, some DOT4 to lubricate, then fit inner seal, piston and then ring with outer seal already in it.

I use a short length of tube that fits over the piston and use a press to gentle ease the ring home. This makes sure that everything is pushed squarely and evenly. Oh yes, and I split the caliper into two halves to make things much easier

I always buy genuine brake parts and have never really had a problem with them.

I used flat metal piece from one of the old pads cleaned up and squashed the rings (pistons an all) in with the aid of a G Clamp
Worked a treat.