Hello Jesus,
You can load 0FI_AP_4 and 0FI_AR_4 data in a DSO (set up a delta also) rather than modifying the info package to load the clearing data.
Create a transformation between FI_GL_4 DSO and the above DSO . Write a routine at DTP level of FI_GL_4 DSO to fetch all the clearing document from the AR AP DSO and load it to FI_GL_4 DSO.
Regards
Gajesh