[tl;dr: Does anyone know how to make own codes? (tutorial plz)]

I have been making moveset changes and balances (with BrawlBox) for a few months with File replacement code [PAL] and gecko. but i started recently using (other) codes - most noticeable hitstun modifier codes - and i have seen the possibility to change chracter specific values (attributes for example) also with codes.
Brawl+ uses this there
http://www.smashboards.com/threads/the-brawlplusery-brawl-codeset-updated-3rd-april.220363/

It doesn't seem that hard if you know how to do that - i seems it would only take a few lines in hex to name the char, the offset/attribute/whatever and the new value.

further more B+ uses a code to set default settings with a code and this should be editable too.

tl;dr: Does anyone know how to make own codes? (tutorial plz)

PS: Code manager only allows 256 lines of codes. Thats why I can't use the full B+ codeset.
      Any possible solution?