According to the SANE website the best you will get with both those scanners is "basic" and that's using the backend :
http://sourceforge.net/projects/hp3900-series/files/Which you could dowmload and compile and install, if it builds against the system (maybe Tex can check this quick for ya).
You can only assume what "basic" probably would be? May only scan at one or two resolutions? Not sure.
If you want/need scanning ability I'd suggest looking at the SANE website and finding a HP that lists as "complete" or there are a few Epson's that run pretty good. A few of the new all-in-ones work well with the new hplip packages.
That is what I see on the SANE home page.
ScanJet G3110 USB 0x03f0/0x4305 Basic Similar to hp scanjet 4370 hp3900
(0.12) sane-hp3900
Sounds like the G3110 uses the HP3900 backend.