Sequences with alpha channel

Hi, I'm wondering if there is a way to load an image sequence such as png, tiff, etc that supports an alpha channel into HeavyM. Or if there is a video format usable that supports alpha.I have a gigantic collection of VFX sequences in .png format and I also use that format to render my own 3D sequences. So I was really bummed out to hit this wall. One thing I tried is loading a sequence in as a playlist. It looks like that could work except that the shortest time each image can be set to play appears to be one second. If I'm missing something that someone could share, that would be great. If not then I think this constitutes a feature request that many users would find useful. Thanks in advance.