The lookahead implementation in opensmt is not yet in the master branch of the opensmt git.  You can compile the lookahead version of opensmt by

$ git clone https://scm.ti-edu.ch/repogit/opensmt2.git

$ git checkout lookahead

$ mkdir build; cd build; cmake ..; make

The binary will be in ./src/bin/opensmt

Opensmt requires the gmp libary for arbirary precision mathematics, and the readline library to compile.