taxable fringe

i need to setup a taxable fringe for the personal use of company vehicles,  sage knowledge base for taxable fringes recommends the in/out pay type.  my issue is that the out deduct gets hard coded to a single liability account and I have no liability to pay.  I need to be able to change the coding on the deduction side of the  to net with the pay on the P&L  (by multiple divisions) so all have left is the tax expense.