It is no rocket science at all, take some batch files and learn about the NPDRM/game update having KLicencee key (the sprx/selfs) scetool cannot decrypt without providing the KLicencee, that's all, for that we use scetool_bruteforce package, place the EBOOT and a sprx/self in the scetool_bruteforce folder and run the tools 
for decrypting gameupdate(sprx/self) using KLicencee key, it's this command
Code:
scetool -l 276153276154879340943492346987 -d file.sprx file.elf
KLicencee is specific to each game so you cannot use the same for another game minus e.g FIFA uses the same key on 12/13/street etc..
then edit whatever needed and resign the files with proper key, disc and gameupdate/npdrm uses different commands, check the batch files, yes it may require some reading on ur end, take a couple hours and some strong coffee and skip true the batch files
then if you like to resign the gameupdate with the KLicencee again add the --KLicencee to the command:
Code:
scetool.exe -v --sce-type=SELF --compress-data=TRUE --skip-sections=TRUE --key-revision=01 --self-auth-id=1010000001000003 --self-add-shdrs=TRUE --self-vendor-id=01000002 --self-type=NPDRM --self-app-version=0001000000000000 --self-fw-version=0003004000000000 --np-license-type=FREE --np-content-id=%cid% --np-app-type=EXEC --np-klicensee=276153276154879340943492346987 --np-real-fname=EBOOT.BIN --encrypt FILE.ELF FILE.SPRX
result: fixed file