If the mosaics are thinner I do this; Mark out as usual. Do the lower tiles up to the border tiles. Now you have marked out the mosaica and you now need to leave that space and continue with the main tiles above. I usually pin/masonary nail these tiles in place and continue to the ceiling.
Once all the wall tiles are complete you can place in the border tiles.
I place the mosaics in the space left for them, measure the depth, then I make a piece of ply over the wipth of the space and on each end cut out the depth, so you now have a template that sits nicely into where the borders will go, obviously minus the mosiac thickness!
Spread in your adhesive, slide your made ply template along the hole, put in the mosaics and use a grout float to press in place, sorted!!!
