Yes, you can either use Tony's Logo Editor (http://www.oro.net/~tfabris/logoedit.htm) which applies the new kernel over the serial port. The other way of applying a new version of the kernel, once you have HiJack installed, is to ftp to the player and upload the kernel to /proc/empeg_kernel

The second method is faster, it takes a few seconds rather than a couple of minutes.