I've been to a couple of those auctions, they are not all it is cracked up to be. If you want good used furniture, file cabinets it is a good place to go. As for tech, you are most likely going to see 5~7 year-old computers, printers, and such, and most of that is going to have the tar beaten out of it. A friend of mine did buy a couple of old PIII 1000mhz and build one out of the two that he bought and is now using it for a Neverwinter Nights server. Wasn't bad for $20USD.
As for looking for information on when and where, try looking on the college's web site. If the laws are similar in your state as in mine (Michigan), then they have to post the dates and times in advance. If you can't find anything that way try to talk to a maintenance person at the college. Maintenance people usually have the best idea when these auctions will happen since they are the ones that have to move all the items being sold. Private companies on the other hand are another story since those auctions are private affair solely for their employees. You could also try the state government or police agencies, this might give you a more places to find what you are looking for. Hope this helps.