Since blockproc uses anonymous functions, you may save your multi-line function into a script, say myFunc.m and then pass @myFunc to your blockproc call.
You may work out a way to manage the sequence artificially using some of those fields. For example, using block_struct.location to skip processing the 2nd block:
function out = myFunc(block_struct)
out = block_struct.data;
Hope it helps!