Clone the xcape repo, install its dependencies:
yum install gcc make libX11-devel libXtst-devel libXi-develthen make, and move xcape to /usr/local/bin.
Create/Edit /etc/gdm/PostLogin/Default, with the minimum content of:
#!/bin/sh
xcape -e 'Shift_L=Shift_L|parenleft;Shift_R=Shift_R|parenright'You can delete the cloned xcape repo folder if you want, or keep it to pull updates and make again in the future.