Is it possible to dual boot Windows 98 or Windows 95 on an iMac G3 running Mac OS 9.2?
Not dual-boot, but you could track down an old copy of Virtual PC for the Mac by Microsoft. VPC was an x86 emulator for the Mac OS X PowerPC line of computers and supported Windows 98 out of the box. I can't recall if it supported '95 as well since it has been several years since I've used it, but I know that it did work reasonably well with '98.
Now as far as how fast it would run that Windows 98 installation ... I don't know about that on a G3. It worked reasonably well on a 1.8GHz G5 and 1.2GHz G4, so I can't speak to a ??? MHz G3.