I'm sure you've heard all of the White/Superba owners talk about the wonderful rib they create on their French knitting machines. I assure you, it's all true... I almost always do my ribs on my 1602, even if I'm going to knit the rest of the garment on my Brother KH860.
But sometimes I want to do a quick pair of socks and I don't want to go to all the trouble of swapping machines around just to knit a couple of ribbed cuffs... so this is how I do my rib cast-ons to produce a nice finished edge on the Japanese machines. Still not as nice as the Superba, but good 'nuf.
Set up the needles for the zig-zag row. I generally prefer industrial rib, but this method should work for whatever your pattern calls for.
Run both carriages across the bed to align all the needles in working position. Position both carriages on the right.
Push all ribber needles to hold with latches open. Then use a ruler (or the flat side of your needle pusher) to push the ribber needles back down so the tops of the needle hooks are even with the gate pegs on the main bed.
Disconnect the main carriage from the ribber (leave ribber arm connected and ribber bed in upper position). Set the main carriage for the tightest possible tension and knit one row right to left with main carriage only. The yarn should now be caught in the needle hooks of the main bed and laying across the ribber needles between the hook and the latch. Carefully push the ribber needles back to working position, making sure the yarn is caught in the needle hooks. Hang the cast-on comb and weights.
Push all of the main bed needles to hold and set the main carriage to knit needles in hold at T1. Carefully knit one row left to right.
Connect the ribber carriage. Push all of the ribber needles to hold, set the main carriage to slip and ribber carriage to knit needles in hold at T1. Carefully knit one row right to left. This completes the circular row.
Set both carriages to knit at MT in both directions. Gently tug on the cast-on comb to make sure the top of the comb is below the needle hooks. Continue to knit the rest of the rib.