short shift gear change.

Just wondering does anyone know anything about installing a short shift gear change to a mk3 astra with F20 gear box.. I bought the quaiffe internal gear linkage second hand which is basically the gear stick and the shaft that goes through the bulk head . We were told this would work but it aint happening for us. If anyone has encountered this before could you please let us know what has to be done or what else we have to get to make it work... cheers!