Justin,
I have tried halochrome a couple of times. It's not easy but worth persevering! I found the most successful agitation is to tip the tray onto one long edge so that all of the toner is collected on one side, then lie the print flat face up in the tray, then tip the tray very fast back to level, and keeping agitating (alternate side-to-side and end-to-end) very vigorously! The first slosh is critical - if that is not totally even you will get uneven marks. This means that your paper should be totally flat, as even a slight curl makes it harder to get even coverage on the first slosh. My best results have been with Ilford postcard paper, because it is stiff and flat, and the small area makes it easier to get an even first slosh. Alternating side-to-side and end-to-end in the tray tipping is necessary to avoid getting stripes parallel to the tip direction.
I think the silvering depends on the paper, as well as the agitation. Resin-coated seems to be easier to manage. The toner runs out very quickly too, so you can't get many prints from one batch, and the later prints look less silvered than the early ones.
I hope this helps a bit. It would be nice to see some prints posted when you have them.
cheers
Pete