You'll need to grab the latest XZip source archive from the XZip home page. Once you've done that, unpack it with our old friend, the tar -xzf command. This will create an xzip directory. Change to that directory.
Before you compile XZip, you'll have to edit the Makefile. Load it into your favorite text editor. Uncomment the SYSTEMFLAGS line directly below the part that talks about definitions for Linux. You will probably also have to uncomment the proper definitions for where your X libraries are. If you're unsure about what to do, try closing the makefile and typing make at the command line. If it doesn't work, type make clean, then edit the makefile again. Scroll down and stick a # in front of the only XINCLUDE and XLIB lines that don't already have a #. Somewhere below that are several different XINCLUDE and XLIB possibilities. Find the one which is appropriate for your system and uncomment them. If that doesn't work, you'll have to go hunting for your X libraries and the associated include files and then put the appropriate path definitions in the XINCLUDE and XLIB lines.
Once you're done editing the makefile, type make at the command line. The program will compile, resulting in the files xzip and xzip.1. The former is the program file; the latter, the man page. To read the man page, type man ./xzip.1. Copy both files to wherever you want them to live. If you want to keep the source code around for later, run the make clean command to remove the detritus of compilation; otherwise, remove the xzip directory.
You can get the source code for Unix Frotz from the if-archive/infocom/interpreters/frotz/ directory of the IF Archive. At the time of writing the most current release is frotz-2.41.tar.gz. Download the source file and unpack it with the tar -xzf command. Doing so will create a directory, most likely frotz-2.41. Change to that directory. With any luck you will be able to type make and end up with the program frotz. Move frotz to its permanent home and then either do a make clean or delete the frotz-2.41 directory.