To my knowledge, the only non-commercial desktop scanners capable of handling large format negatives are the Epson 4990 and Epson V700 (and possibly the V750 which I think is a slight update of the V700). I don't think any of them are made any more, but you can pick them up frequently on eBay in the $300-400 range. The last time I was researching scanner options for some 8x10 negatives that I had was about 3 years ago, so I guess it's possible something could have come out since that I'm not aware of, but at that time most others would only handle up to 2-1/2" width negatives or transparencies, if even that.
I think Mark (lordstan) had some limited success with scanning some large format negatives in multiple strips and then using Photoshop or something similar to merge/stitch them together. It seems like a pretty labor-intensive process, especially if you have to scan very many, but if you're just doing a handful it might be worth trying as opposed to buying another scanner.
Hearing so many people having problems scanning their newly-acquired negatives makes me think I should start a large-format negative scanning service
