Searching for "The Cat Who Walked Through Walls"

[Teek]

So, I figured this was a good place to ask around about this. 

  When I was younger, I read a book which I THINK was entitled "The 
Cat Who Walked Through Walls" or some variation thereof. It's NOT the 
Robert Heinlein book of the same name. It's a science fiction 
children's novel most likely written in the 1970s or 80s, absolutely 
no later than 1990. It was about a society in which cats and humans 
were equals and communicated as such. There was a radical new science 
which involved merging the body and mind with objects. The was 
someone who had merged with a space ship and refused to come out, and 
someone who merged with the entire universe instead of dying. Oh 
dear. This sounds like it makes no sense, but I swear, it did. The 
copy I read was hard cover, white, and had a grainy slightly pastel 
colored photo of cats on the front cover, and the first scene had 
something to do with commuting on a train. 

  So, have any of you ever heard of this book? I read it once when I 
was younger, forgot all about it until years later, and have been 
trying to track it down for ages. I am beginning to think I'm crazy 
and imagined the whole thing. Maybe someone can suggest a resource 
which'll track down books without a definite title and no author? No, 
didn't think so.

much thanks if anyone has any leads,
Perplexed!Teek