Not sure if it is the same file lister as the one on snitzbitz, but if it is then you need to look in file_lister_uploader.asp
for the filetypes, look around line 260-280, it checks the file type and sets a variable allowed to 1 or 0 based on the file type, you just need to override that and force it to 1, similarly the filesize is checked a few lines below that. You may need to make changes to IIS to allow very large files