Mike, I've got several planes with pull/pull set-ups. On the WWI fairly low speed stuff I run the cables right off the servo, but on a couple of higher powered acrobatic planes I use a belcrank to carry the loads. Ball bearing servo are best if you are going to hook up directly.

The route of the cables isn't critical, most of mine cross, but the distance between the cable ends at the horns and at the servo or belcrank must be identical or you will get changes in cable tension. Also you don't have to have the cables bow string tight, just make sure it is the same for both cables.
Walt