http_load can be downloaded as a source .tar file (which was named .tar.gz for me, though it is not gzipped). The version as of this writing is 12Mar2006. Unpack it to /usr/src (or another path by changing the /usr/src) with:

$ cd /usr/src && tar xf /path/to/http_load-12Mar2006.tar.gz
$ cd http_load-12Mar2006

To add SSL support we need to find out where the SSL libs and includes are. I assume they are in /usr/lib and /usr/include, respectively, but they may or may not be the same on your system. Additionally, there is a "SSL tree" directory that is usually in /usr/ssl or /usr/local/ssl and contains certificates, revocation lists, and so on. Open the Makefile with a text editor and look at line 11 to 14, which reads:

#SSL_TREE = /usr/local/ssl
#SSL_DEFS = -DUSE_SSL
#SSL_INC = -I$(SSL_TREE)/include
#SSL_LIBS = -L$(SSL_TREE)/lib -lssl -lcrypto

Change them to the following (assuming the given...