you can not copy or move a project plugin to another and expect it work.
Win7PESE have its own .net plugin.
Trouble seems to me,
There is no contribution to Win7PESE project for .net 4
Maybe there is no .net 4 on Win7 cd
you can get ideas from other plugin of other project,
but in final you need to create a .net 4 plugin for Win7PESE
and better contribute around