Procedure
Extract the .jar or .zip file of the application to a folder. Locate the directory or folder using this application, press Embedd and allow application access. Go to the extracted directory or folder, replace the image mysplash.jpg with your image and note that the name and format must be the same. Repack the files using BlueFTP or PowerGrasp.
Note: If the application fail to embedd splashscreen, edit each parameter in MANIFEST.MF starts with a new line.
Dont forget to set your file permission as Always Allow.