My H's involvement with the kids has also been an issue in our house. We define spending time with the kids differently. I see it as one-on-one attention, playing games, reading etc. He on the other hand feels that if he is working on the car in the garage and the kids are in the yard, he is spending time with them. I have nagged him to death about taking an interest in the kids but nagging, of course doesn't work so I have decided instead to use "gentle guidance". For example, I suggested that this weekend he take the kids sledding. It is an activity where he will be focused on the kids, not on his car, the t.v. etc. AND since I don't like the snow.....I will get a little me time (kill two birds, eh?). I think that any behavior change happens over time. If I make enough suggestions then hopefully over time, he will initiate the activities himself.
