I've got the TJ version, which didnt have any holes either. I've no idea whats involved with the side bits on the TS that go up the wheel arch, but the front edge mountings much the same as the TJ.
I used the original lip as a template...I put masking tape along the Seibon lip mounting face, positioned the old lip on the Seibon one back to back and held it there with mini G-cramps. Take time to line them up edge to edge as best you can.
I marked off through the original holes onto the masking tape, and drilled the Seibon with a drill large enough to accept the square shoulder on the original bolts.
The old bolts / alloy backing plates are a bitch to get off, especially if the bolts are seized...you may need to remove the undertray, and be prepared to have to buy new backing plates as the old ones are easily snapped.