Well the only way I can see you managing that is to analyse the makefile to see where everything is dumped by the installation process.
What machine are you trying to compile it on, does’nt take an eternity to build it? I would have thought that just writing a bash script to do it all on each machine at once while you make a cup of tea would be a good bet?
Then, download OpenWRT from its development SVN trunk (read this), configure it for x86 [v2.6] as the Target System, and select asterisk14 under the Network sub-menu. This will compile asterisk-1.4.11 (among other packages to generate) and generate a bunch of asterisk packages in .ipk file format. Hopefully, a Debian Linux distro will understand a .ipk file to install on its system.
BTW, the patches for asterisk-1.4.11 on OpenWRT SVN trunk can get patched all the way to asterisk-1.4.17. For asterisk-1.4.18, you probably will need to create your own patches for the getifaddrs because asterisk seems to be unable to link with the getifaddrs from the uClibc package.