Deep breath, coz this is one massive post!!!
Dave, as you rightly said, Lepsons WILL do them, but they wont put them back together. What you will need are the rubber seals or "gaskets" from BBS or
www.felgen-man.de
The REASON Lepsons wont put them back together is that it takes too much time! Its as simple as that! Any d1ck with a torque wrench can put them back together if they get the seals sat correctly and the bolts done up in sequence -
insert one bolt and do it up to touch the rim, then do one up on the opposite side of the wheel. then go 90degrees to that second bolt and insert and do number 3, just to touch. go opposite to number 3, so u have a "4stud" arrangement like the 4x100 fitment of the e30 wheels, except in the rim.
Work in a clockwise manner in this same sequence all the time. doing them up to touch the rim. when they are all in, pinch them down a bit more IN THIS SAME SEQUENCE and work them GRADUALLY up to their torques (you will have to speak to BBS or Felgen-man for these.) As you see, this will be VERY time consuming, and this is why Lepsons arent interested in split rims generally!
Once they are back together, only then can you have the tyres put back on (obviously)
Placey, you have the idea with the spoked wheels - you always work opposite to the bolt you are doing. (im into bike wheel building too, so i know what that guy meant.) It isnt complicated, just time consuming.
Dave again - ive seen rims done by Spit too while at Ants, and ur right, they arent quite as good, but they are slightly cheaper - "pays ur money..."
Panesar, i dont know about Spit not doing splitties, coz i dont know, but they WILL do bent rims! I have seen an bent alpina (genuine one) done by Spit so i have seen the evidence to say that they do, do them (no dig or 'ner-ner ne-ner-ner' intended)
Dave, lepsons will tell you Ԛ£75 per alloy - i know coz i got the same quote.