One of the most nerve-racking parts of a bride's wedding day is fitting into that dress. The tailor took measurements weeks or months before, and your weight and shape may have changed slightly between the fitting and the big day, making quick alterations necessary. Making a lace-up corset back for the dress can save the day.
Remove the zip seams, starting from the top, with your seam ripper. Remove only as much as you need for the dress to fit, probably down to the waist. Cut off the zip tape that you've removed, but be sure to leave enough to fold the end and stitch it inside the lining.
Make corset loops with a sewing device called a "fast turn." The loops will hold your tie when you fasten the corset -- much like the eyelets in a pair of trainers that hold the shoelace. You can get a "fast turn" at a sewing shop. It has two parts: a wire with plastic at one end and a brass tube. Take some white fabric (chiffon is one possibility) and cut it into strips that are about 2.5 cm (1 inch) wide and 45 cm (18 inches) long, using scissors. Fold each strip lengthwise, matching right sides, and sew all the way down. Slide the brass tube all the way into the strip until it comes out the other end. This, slide the wire in until the end comes out, and pull it back through. The end of the wire will pull the fabric back through. Cut the long tube into sections that are 3 cm (1 1/4 inch) long; each one will become a loop.
Draw your corset pattern on paper, making sure that all of your loops have the same distance between them and the same width. One good source for your pattern could be a corset from a friend's dress or an attic sale. Set the loops on the paper and then use your machine to sew down the centre of the loops, picking them up off the paper when you've reached the end.
Pin the first loop in, leaving just enough of a gap for the tie to fit snugly. Pin the second loop so that they form an "X" on the inside. Add the rest until you've covered the gap, and sew the loops in, using stitches like those you would use to put in a zip -- small and tight.
Run the ribbon through the loops, adjusting it evenly, like a shoelace, until the back of the dress is pulled together comfortably, and tie it off at the bottom.