If you want to know how to trim or swap the hoses on your prebled shimano hydraulic disk brakes you've come to the right place
Recently a friend of mine asked me if he could swap the hoses round on his shimano hydraulic disc brakes without having to bleed them. The answer "Yes, shimano have a guide to trimming brake hoses without bleeding them on their site". 10 minutes later he inform's me they don't.
Well they did but it appears the link has gotten killed in their site redesign, it appears in google but 404's you are in luck though!
Here is a link to the copy i had luckily saved - https://www.dropbox.com/s/70z5v90axvtcn1o/Shimano-Brake-Hose-Trimming.pdf.
Edit: since writing this and rehosting the PDF i've stumbled on this post by epicbleedsolutions which is nicely laid out and clear. I'd probably use it over the pdf - http://www.epicbleedsolutions.com/blog/shorten-shimano-hoses-without-bleeding. Also worth noting epic do an excellent bleed kit, tis what i use much better then the stock shimano one
Enjoy, should apply to all shimano prebled brakes - certainly does for deore, xt and xtr.