yep I did a similar thing on my r56 Cooper. You want to try the following

1. open the bonnet
2. remove the clips (best way to do this is with something flat to pull out the centre and then the actual clip machanism just pops out - a pet monkey's teeth are fantastic tools!!)
3. check the lower mechanism next to the chrom stripe. There should be a release catch in the middle and at each side. The lower chrome strip should slide out.
5. take off the grill