No way to do it without two pumps
A macerator is essentially a blender...it has to have power. Manually pumped unmacerated waste wouldn't make it through the macerator without clogging it up. So the only way to do it would be a separate pump, plumbed to bypass the macerator. However--The major power hog in a macerating toilet is the raw water intake pump, not the macerater pump. Macerating electric toilets that use raw water draw about 30-35 amps/flush...those which use the fresh water solenoid option draw about 10 (which, btw, actually translates to about the AH consumption of a VacuFlush, which draws 5-6 amps, but for 3 times as long). The freshwater solenoid option also reduces the flush water consumption in most macerating electric toilets by about 75%, so your holding tank doesn't fill up as fast either. So the solution to your problem--IF it's available for your toilet--is to replace the raw water pump with an optional fresh water solenoid, or replace the entire toilet with one that offers that option. I don't recommend DIY conversions...factory options include the necessary check valves, anti-siphon devices and backflow preventers to protect your fresh water supply from contamination by the toilet. The toilet mfrs know what they're doing, but what looks like it should work to a DIYer may not.