If you installed the HOWTO's then you might want to read /usr/doc/Linux-HOWTOs/Ftape-HOWTO for the basic info. There is also a kernel doc concerning ftape in Documentation/ftape.txt. You will need to download and install the kernel source package for 2.4.20 for the kernel sources. I highly suggest the kernel doc first though because the HOWTO is about 5 years old.
There is a module called "ftape" that you may need to load as well. (modprobe ftape) I do not know if anything special is required for parallel port support. The ftape interface was written primarily for QIC-80 drives using the floppy drive interface controller. But it appears that it will also support the parallel port operation.
My personal experience has been with IDE and SCSI TR-4 tape drives. But once the character device interface is established it shouldn't make any difference. Exception might be that QIC-80 tapes may need to be formatted. So perhaps the info above will be of some help to at least get you started. You could also try searching for "ftape" on http://www.google.com/linux