I want to either have a button on link on my form which can take the ID and show respective details for that that record?

For e.g. Let's say I have EmployeeInfo form and VacationRequest form. In the VacationRequest form, I have lookup called EmployeeName that displays all employees. I want to give a link or button right next to the EmployeeName look up field where the user can view the Employee details, in a popup, without leaving the VacationRequest page.

Question: How do I add a button or clickable link in a form? I can use deluge to generate the link dynamically.

Regards,

Shashin