Try an editor of you choice. At the very least your system probably has vi or vim or joe. I use nano.
You'll need to find where httpd.conf resides, which seems to vary somewhat. If you don't know where it is, you could peer inside your init script if you have one, ie. "less /etc/init.d/httpd" (or "less /etc/init.d/apache2", or something, do "ls /etc/init.d/" to see what the script might be) and look around for clues to where httpd.conf is. Otherwise if you have locate, you could try "locate httpd.conf". (you might need to build the locate database first, "locate -u", and sit back for a bit.)
From your telnet command prompt do "vi /path/to/httpd.conf" with the obvious replacements of your choice of editor and /path/to.
PS. If you use vi, I can recommend having a look at an online manual for how to save, quit, cut, paste, etc.