Customizing and extending TREX to add Email ID in search

Hello Experts,

We are using TREX for Succession Planning and have a requirement to add a new field Email ID in search options for talent:

Field name: USRID_LONG from IT0105 Subtype 0010

Kindly help with the steps applicable around customizing and extending.

Thanks in advance for your guidence.

Best Regards,

Rahul