A patch making makepkg install custom license automatically by huntxu (mhuntxu[AT]gmail[dot]com)
--- makepkg.orig	2009-10-02 22:40:42.711085370 +0800
+++ makepkg	2009-10-02 22:43:47.333083311 +0800
@@ -984,6 +984,12 @@
 
 	write_pkginfo $nameofpkg
 
+	# check for a custom license
+	if [ ! -z $licensefile ]; then
+		msg2 "Installing custom license..."
+		install -Dm644 ${startdir}/${licensefile} ${pkgdir}/usr/share/licenses/$pkgname/${licensefile}
+	fi
+
 	local comp_files=".PKGINFO"
 
 	# check for an install script
@@ -1180,6 +1186,11 @@
 		return 1
 	fi
 
+	if [ "$licensefile" -a ! -f "$licensefile" ]; then
+		error "$(gettext "Custom License (%s) does not exist.")" "$licensefile"
+		return 1
+	fi
+
 	local valid_options=1
 	local opt known kopt
 	for opt in ${options[@]}; do