Why can't gcc find libevent when building tmux from source?

I want to install tmux on a machine where I don't have root access. I already compiled libevent and installed it in $HOME/.bin-libevent and now I want to compile tmux, but configure always ends with configure: error: "libevent not found", even though I tried to point to the libevent directory in the Makefile.am by modifying LDFLAGS and CPPFLAGS, but nothing seems to work. How can I tell the system to look in my home dir for the libevent?