This picture shows how the legs were drilled using a wood jig. The legs are clamped onto the jig and the jig is clamped to the lathe bed - for want of any free space in my tiny workshop.
This is a view of the drilling jig. The "L" shaped wood piece is what the legs are clamped against when the legs are drilled. Here the jig is set against the pedestal for drilling the holes in the post.
To ensure that the holes are drilled at center I used a mallet to mark the holes against the live center in the tailstock of the lathe. The legs are attached to the pedestal with 3/8 dowels. Since the jig was a little sloppy I used epoxy glue to attach the legs to ensure filling any small imperfections. I intend improving the jig by adding a piece at the bottom to allow clamping the jig to the lathe bed and enlarging the cheek block for clamping the legs. I also ordered some steel inserts to add to the jig to make the holes more accurate.