Here is a wonderful guide http://fwlbucket.s3-website-ap-southeast-1.amazonaws.com/assets/multimediams/media/TC_YFLEX2_RET_Imp-Guideline_CWW-v1.0.pdf

Here is some sample policy language:

Alternative work schedules, including the compressed workweek, are consistent with [company name] efforts toward work/life balance.  

A compressed workweek allows full-time employees to work longer days for part of the week or pay period, in exchange for shorter days or a day off each week or within the same pay period. 

Compressed workweek schedules must be set (not varying from pay period to pay period), and may be any of the following [for a two week pay period]:

Eight nine-hour days, one eight-hour day and one day off every pay period.
Four ten-hour days each week and a day off each week.
Four nine-hour days and one four-hour day each week (one afternoon or morning off each week).
Four seven-hour days and one twelve-hour day each week.

Compressed workweek schedules must meet the following requirements for consideration:

All full-time employees must work a 40-hour week (or 80-hours each pay period).
Operational requirements must be met.
Service to the customer must be maintained or improved.
Costs to [company name] will not be increased.
Each office or operation must be covered during normal [or core] business hours.

Requirements for compressed workweek approval include:

Employees must request a compressed workweek schedule in writing. The decision of the [manager or supervisor] is final.
Managers and supervisors are encouraged to approve employees’ requests for compressed workweek whenever it is possible to do so without compromising the organization’s goals.
In positions where a compressed workweek schedule is permitted, all new requests from employees or any type of change in work schedule or work hours will be considered on the basis of the above requirements for consideration and the workload of [company name].

Approved compressed workweek schedules will meet the following standards;

Compressed workweek schedules will not diminish the ability of [company name] to assign responsibility and accountability to individual employees for the provision of services and performance of their duties.
When a paid holiday falls on an employee’s regularly scheduled day off, the employee will be given another day off during that pay period.