Check this post out, there's information I posted some time ago
http://www.rcuniverse.com/forum/m_39..._2/key_/tm.htm
On foam wings with tubes, I just stick the hose into the tube. My breather tube is a Sullivan Nirod outer tube (Blue) drilled with 1/16" holes every 1 1/2" or so, somewhat random, this is caputured inside a piece of rag material, nothing fancy. To be honest, I rarely use a tube, just try to locate the end of the vacuum hose on an area where a small indentation doesn't matter.