Learn MQL4 (it's similar to C) and recreate the functionality you need. This builds valuable skills.
Many developers will sell you the source code for an additional fee. ex4 to mq4 v4 0 224 1 decompiler extra quality
: Search the MQL5 codebase for free, open-source versions of the tool you are trying to modify. Learn MQL4 (it's similar to C) and recreate