Accessing settings from another project in an sbt task

gistfile1.scala

lazy val webAggregateImpl = webAggregate := { mappings: Seq[PathMapping] =>
  def go(m: Seq[PathMapping], p: ResolvedProject): Seq[(File, String)] = {
    if (p.dependencies.isEmpty) {
      m
    } else {
      p.dependencies.map({ dep =>
        val subp = Project.getProjectForReference(dep.project, buildStructure.value).get
        /*
        At this point I have a http://www.scala-sbt.org/0.12.4/api/sbt/ResolvedProject.html ... so I can access project
        certain properties of the project, like base, id, etc.
        
        However, that's pretty limiting. I'd like to be able to access ANY setting from the project. So one way I tried to
        do that is to get the ProjectRef and access in with "in", like:
        val temp = (target in dep.project).value ... but that fails with the exception:
        
        error: Illegal dynamic reference: dep
        val temp = (target in dep.project).value
                              ^
        */
        val newFiles = (subp.base / "app" / "assets" / "js").***.get.toSet
        val newMappings: Seq[(File, String)] = newFiles pair relativeTo(subp.base / "app" / "assets")
        go(m ++ newMappings, subp)
      }).flatten
    }
  }
  val newMappings = go(mappings, thisProject.value).distinct
  SbtWeb.syncMappings(
    streams.value.cacheDirectory,
    newMappings,
    WebKeys.webTarget.value / webAggregate.key.label
  )
  newMappings
}