Hello Nikon,
I tried to use feature navigator
http://www.cisco.com/go/fn
search by feature, filter= BGP and then I selected item .#60 " BGP support for 4byte ASN", then continue but ME3600 is not listed among the platforms supporting the feature.
However, ME6524 is listed as are C6500 - 7600.
I tried also starting from the platform to see the listed features for the last 15.2(2)S, but the list of features is quite short and does not appear complete
Edit:
The 15.2(2)S configuration guide does not provide any info either
see
http://www.cisco.com/en/US/docs/switches/metro/me3600x_3800x/software/release/15.2_2_S/configuration/guide/swiprout.html#wp1226539
You should contact your Cisco representative
Being a new platform it should support the 4byte AS number.
Hope to help
Giuseppe