You should have a lot of folks weighing in here.
I based my system on what I've seen and used in other boats. Found some 2" webbing and measured out the first length from the mast step to the aft end of the CB trunk, allowing for adjustable outboard pull.
The second section starts from the same aft CB point and extends to the aftermost part of the seat. This section is great for extra leverage (skipper) needed downwind.
I put grommets in the doubled-over ends, attached a stainless ring to the mast step track, screwed eyestraps into aft end points on trunk/seat, and tied it all in with adjustable lengths of 3/16" line.
As all of the above was thrown together just before a regatta 4 years ago, it's due for some revision. So, I'm all ears as to what others have done, especially with that troublesome thwart in the way!
Here's another thread on this topic:
viewtopic.php?t=614&highlight=hiking+strapsAlso, check out Phill's photos:
http://forum.daysailer.org/forum/gallery/search.php?user_id=66