Look at my thread I just posted of my S60 install. You may be able to dremel enough to get it to slide on, it is gonna sacrifice strength though. That is if you can even take enough off to get it to slide over. There is a pic in my thread of where I cut it and bolted the two halves on with the LCA and everything, once in place you can weld the two pieces of bracket back together. It takes some hammering and bending, but I think it will be stronger than dremeling the inside of the brackets thin enough to slid over the LCA bracket. Good luck with it!
'99 Camaro Z/28 M6 - 430rwhp/400rwtq
Ported 799's/Tick Performance "SNS2" Cam/Bolt Ons, 4.10 S60, TUNED BY BLUECAT