Not much data out there....
on the 45 gr. Hornady bullet. It is a soft-point, unlike the ballistic-tip V-Max available in 32 and 40 gr. I've seen it on Midway's site, but I can't find any loading data for it. I'd like to try some.
You might try contacting Hornady. They may be able to point you in the right direction. Otherwise, the best you can do for now is use the 50 gr. data as a starting point, from the link Scott suggested.
As far as I can tell, the only manufacturer other than Hornady making a .204 bullet 45 grains or larger is Berger, with their 50 gr. match bullet. My guess is that you are going to need a pretty fast twist rate to stabilize that bullet.
Hopefully, given a little time, more data will become available for this great caliber.