Guys, the aluminium frame is not that fragile as you might think. Aluminium is pretty strong and it will withstand more abuse then you might think.
The whole secret lies in good lubrification. Just put lots and lots of grease and the arms/spring pans will slide into the frame. With the use of a hydrolic jack it will go even easier. Just don't put any washers in where you are pretty certain they wont fit. I still have got most of mine in PF boxes. I've used just 4 (?) all the others are of no use and are probably a mistake when packaging.
Spring pan: absolutely no washer can fit between the subframe and PF bush. Just be sure to flatten the welding done by Alfa, or the bush will not go 100% in and you will have some trouble fitting the pan back on. Washers probably needed for where the pan gets inserted to the wheel - and that's the only place I needed them.
Tranverse arm: no washers needed for where the arm gets attached to the frame again. No washers for the shock absorber too.
Fork shaped arm upper arm: I havent done this one yet, but probably need 2 washers, just to keep the arm from touching the frame directly on one side since the PF bush gets this job done on the other.
All in all you need 4-6 washers and that's it. Just remember - eventhoug it says/is packaged in a certain way, if there isn't a single mm of space left for the washer it won't fit, no matter how hard you try to put it in. The worst thing you can do is force something and something may snap. Just use a lot of grease and some common sense and it will work.