Here’s a quick view of the Box Stitch for double-loom knitting, taken from the Knittingboard Chat. There’s a great comparison there of the Box Stitch and Criss Cross stitch, as well. Check it out here.
Box Stitch – First row starts with needle #1 to #4 and weave every other needle.
The next row starts with needle #1 to #3, then weave consecutive #2 down to #5 and then every other.
Images courtesy of Knittingboard Chat.