Boost Graph Library

I've given up on trying to understand the documentation on the subject, so I'm turning to you in the hopes that you can tell me what I need to do.

My problem is deceptively simple. I have a directed graph. Each vertex has two properties, a pointer and a numeric ID. Using the bundled properties, this is easy to implement. The edges have no properties.
I know how to add and remove vertices and edges. This is not a problem either.

At one point, I want to grab all vertices with the ID 0 or 1 (OID_NULLOBJ and OID_EXPECT in my code) and start a DFS/BFS (doesn't really matter) visit from each one, colouring vertices as I go. After I've done this, I want to find all uncoloured vertices.
In other words, I want to find all vertices that are not reachable from any of my start vertices.

The problem I have is with the external property map I need for the algorithm, and the visitor.

To illustrate:

Code:

---

A ---> B <---> C

D ---> E
 \    |
  \    V
  --> F <--- I

G <---> H

---

If A and D are my start vertices, I want I, G and H to be uncoloured after I'm done.

Any help greatly appreciated.

Do you need help with the alogrithm itself or the code needed to perform it?

Only the code. The algorithm is pretty straight-forward. I just need to paint all vertices reachable from the root vertices, and afterwards collected the unpainted ones.