locking control surface to device via M4L

Hi All
Anyone have an idea how i can Lock and Unlock devices from a control surface using Max4Live. I run 2 Remote sls (sl 37 and zero). I've got some useful navigation going exploiting the automap function and the select_device call in M4L to flip through devices on the one surface, but if i set the other to enable automap i just get a duplicate of the first which is really no use at all. I'm thinking that using the Lock to Control surface is another way of navigating devices, but i don't see a function that may do this in the Live API Reference.