Whilst BingBot has a Webmaster Tools section that allows you to limit the speed at which the bot crawls your site, there are three major problems with their approach.
They don't allow you to select a crawl rate by number of seconds like Google do. Instead they have a crappy low to high range, but make no attempt to explain what low and high actually mean in terms of seconds between hits.
BingBot may adhere to your wishes to crawl at a slower rate, but they often have multiple spiders crawling your site at the same time. Many spiders crawling at a low rate can be far worse than one spider crawling at a high rate.
Microsoft don't care. I have contacted them about instances where they had around 20 individual bot connections to our server loading pages every few seconds and bringing the server to a halt. Their response was that there was nothing they could do about it.
A simple bit of programming skill by Microsoft could easily ensure that only one bot crawls a site at any time.
My solution is to limit the MSN IP ranges in iptables. I'm still experimenting with this, but I believe this can still allow them access to the sites, but force them to slow down. When the connections become too aggressive they are rejected.