In Celoxis you can define a per hour cost rate for your resource. Celoxis lets you define 2 rates, a regular and an overtime rate per resource. This is done at the Company level by a person having Admin access.
You can override the company level user cost rate at a project level if required.
Note: To override rates at the project level, the user (or the Project Manager role) will need to have View and Edit project financials permission.