The Scissor Clip Lock at the bottom of that page looks like exactly what the OP was looking for.
Unfortunately, you're still limited by the very flimsy universal laptop lockdown slot.
IMO, the cheapo style cables are good enough. They provide security that's right in line with the tiny (easily broken) lockdown slot.
If you want more security than those provide, then the adhesive style of lock plate is the way to go. Most of those adhesive loops are 2" x 2". Some are as big as 4" x 4". With 16 square inches of adhesive, those loops will never come off.
...of course, then you've got a big ugly chunk of metal glued to your notebook...