Set the value of $CVSEDITOR or $EDITOR to denote which text-editor to use to write the log while committing.

[rishi@Sunflower ~]$ export CVSEDITOR="emacs -nw"

Adding the above line (the part after the $) to ~/.bash_profile or /etc/profile would also be enough, depending whether you want to make system-wide changes or user-wise changes.