The hydraulic preload saves you the hassle of C spanners,the ride height will be at the bottom of the shock,put the original shock back on,measure the height at the back,put the Wibers back on and start again,or just put e'm side by side,ajust the Wilbers accordingly it'll give you a starting point.
If you have not got ride height adjustment then you should not be able to adjust the ride height. The preload is there to set the load on the spring i.e. the amount it is allowed to compress till it bottoms out. If you want me to help you set the preload (sag) on your bike then give me a shout.
As regards lenght of shocks, the 02/03 BCR shocks were in fact shorter than the standard 'S' I do not know the lenght of the 04 BCR but the shocks you have are 318mm the same as the standard 'S'. The 02/03 BCR is higher than a standard 'S' because it has the shorter torque arm.
Andrew
A man can fall many times in life but is never a failure until he refuses to get up
What you gotta realise there ain't no such things as standard suspension setting,when you've got your head around sag,preload,compression and rebound,you'll then find out what works on a crap road at 60 is rubbish leaned fully over at 120,even with a good shock there's non of this 'One size fits all'
I'd set the preload at less than half,normally if your useing half of the preload or more you've got the wrong spring on,the most important thing about setting up suspension is knowing what you want!!!,it's the art of bikeing,trouble being a lot think it's buying a helmet the same colour as their bike!!!!