They're less likely to give you a suggested mashing regime, than to give you a detailed analysis of the malt and assume you know enough to work out for yourself how you need to treat malt like that to get the result you want. The websites of the companies involved sometimes give quite good descriptions of the brewing properties of their malts - and an e-mail to them might well get results too.
Funnily enough - what Nick said is "bollocks" can often be quite true - not completely true of course, but somewhat so. Malt can be, and often is, quite temperature stable. It gives a very similar fermentability profile mashed accross a quite wide range of temperatures. This is often desirable for major brewers who are brewing a lot of similar styles of beer, as it allows them a little leeway in their systems without changing the result too much.
So while if you are using a malt designed primarily for small craft brewers who want a malt they can manipulate all over the shop - say a marris otter or something like that, you can make a fair amount of differnece to the final beer with temp rests - If however you were to get yourself a bag of something like Schooner originally destined for a big brewery, you'd have to flog the hell out of it to make much of a difference to the fermentability profile - its designed to be stable.
Darren is spot on - general mashing guidelines are just that... general. If you want to get right down to specific results of subtle adjustments, its going to depend on the specific malt, from the specific maltster and even the specific season, region and batch of malt in question.
