Probably Talend should open a project to host contributions as "talend custom components library"?
A google search reveals tutorials on how to build custom components but I believe an open project to host the additional components will only help.
Please correct me if I am wrong but all I see about "Dynamic Schema" refers to TalendIntegartionSuite_Studio_UG.pdf which is only available with a paid subscription meaning is not open source.
I ended up creating a tFileInputCSVFilter available in github together with a tutorial to build components https://github.com/nestoru/talend-custom-components
I have added a sample on how to use it in my blog http://thinkinginsoftware.blogspot.com/search?q=csvfilter#talendComponent
This component is really simple. There are 4 params to be used and the picture should be self explanatory.