scim-input-pad is an OnScreen input pad for SCIM used to input some symbols very easily. It requires scim 1.2.0 to work.
All symbols are stored in text data files. See README in the package for details. You are always welcome to contribute us new data files, suggestions and bug reports.
It's also a demonstration of how to write a SCIM standalone Helper module. If you want to write similar applications, like OnScreen keyboard, handwriting input pad etc., you may read the source code of this project.
You can download the source package from the download section of http://sourceforge.net/projects/scim.