The mentioned 154 Mbps by your carrier make the access technology smell like ATM.
LACP over ATM might create some issues
Therefore as you have a CCR you might ask your provider to host a small mikrotik for you at one of their PoPs near you.
using eg. EoIP-tunnels over each 100M link you get you could bond those together and aggregate those links.
in case you can get your provider to deliver 2 x 100M as LACP link to your C3750 you should take that offer, it's as simple as setting up a Port-Channel interface and you're done.
EoIP bonding is described in a quite similar fashion (wireless instead of two carrierlinks via ATM) here:
http://wiki.mikrotik.com/wiki/Manual:Bonding_Examples
Regards
hk