That is not a currently available function.
However, it is possible to make each page have more posts/threads on it. In the "My Profile", you can go to "preferences". Scroll down to "Linear Format Settings".
In the "Threads Per Board Page in Linear Format" field you can put in a number of threads you would like to see per page. The default is 50, but you can have up to 200.
Directly below this is "Messages Per Thread Page in Linear Format". The default for this is 10, but you can set it to have up to 50. That should make a huge difference in how many pages you have to wade through.