I presume that many Countries allow Employers to "loan" money to their employees, but each Country has it's own regulations regarding the interests to be charged on that loan, the period the employee has to pay it back, etc...
As to how to configure such a WT, the Model to use could be Country Specific but you should be able to find an "Advance WT" into the WT Models for your Country Code. You may need to modify some values in Processing Classes, and you'll have to identify where would be the best place to add it to your Remuneration Statement and Payroll Journal.