this is for Synfig and Moho. I couldn't find an easy tool to do this online, so I made this one. This just makes your job slightly easier. {{{{{Export only works if you click "see inside"}}}}} Info taken from http://www.lostmarble.com/moho/manual/index.html?switch_layers.html
you start with a folder full of the images you want to import as a sequence. write the names of each image, one at a time, into the text box at the bottom. when you're done, click the green check mark to generate your file. then right click Output, and click export, and name it <anything>.lst (LST) if you already have a list of file names, you can right click and import that into "list of images" as well.