Pre-germination of grass seed
The best time of year to plant cool season grasses (crested wheat and others) is from around Aug 20 through Labor Day. You are right in suspecting that seeding at this time of year would be tough. You can pre-germinate the grass seed, but you will still have to maintain a moist seed bed, particularly since you will have started the germination process and there's no turning back. It will be difficult to do going into the hot time of year.
From what I've researched, it appears that cycling the seed through soak/drain cycles helps improve percent germination. So you'd submerge seeds for 12 hours, drain for that amount of time and then soak again. Drain away the excess water before planting.
What type of lawn do you have now? Is is crested wheat or is it mostly Kentucky bluegrass? Kentucky bluegrass is a sod former, crested wheat is a clump-former. The two growth habits don't make for a uniform looking lawn. In addition, crested wheat is more blue green or light green in color than Kentucky bluegrass and that plus the clumping habit may cause the lawn to look weedy or patchy. I would caution against this combination for these reasons. If you are sowing crested wheat into crested wheat, then the uniformity/coloring shouldn't be an issue.
The lawn is a mix now including bluegrass, western wheat grass and crested wheat. I'm trying for a lower maintenance yard than KBG. I'll give the seed soaking a try, then if it doesn't work I'll try again later.