@giannibyte 

If the value of the contribution is built into your employee's salary, the salary paid to that employee for providing the service is your charitable contribution.  There's nothing else to do.

You cannot deduct the value of a service as a charitable contribution and also deduct the same pay to that employee for the same time spent on the contribution.  You would be deducting $2 for every $1 spent to pay your employee.  Does that makes sense?  This is also why you're unable to get this to work in QB because you have no reduction in assets - you haven't given anything for this "contribution".

Also, the IRS is very clear that you cannot deduct the value of a service provided as a charitable contribution.