I made some customization in service management for internal use.
On service item card, I added new field FA code.
On service order, I inherit this value and I choose option Maintenance or Acquisition Cost in new added field.
In posting, depends of pevious setup, I post additional entries in FA entry (Maintenance or Acquisition Cost ).
All other depend of GL posting setup.
If this is not enough to self customize, try a some vertical solution.