Check out the Select Products catalog at:
http://www.selectproducts.com/product/fuses.html
Both the high amp MIDI and MAXI fuses are slow-burn, designed for automotive applications. A fuse block is available for both.
Fusible wire (arranged in parallel) can be used but it would look a bit messy.
Or you could find a local automotive audio installer to do it for you. They deal with high amp systems every day.