Like others here on this forum, I also struggled with the pins of the wire wheels, especially when turning it over to align the inner rim spokes. So I got some 8mm OD nylon tube and found that it needed about two wraps of insulation tape. This then goes into the center hub. I inserted a 4mm bolt through the nylon tube and wheel with a couple of washers and nut. When tightened up it expands enough to keep all the pins in place whilst I turn the wheel over and align the spokes, then tighten down the inner wheel rim.
Please see attached photos. These were obviously taken after I'd put the tyre on after a soak in boiling hot water... good excuse to stop for a coffee.
I hope this helps some of you.