The 7.62x45mm is a collector's cartridge. Only the Czechoslovakian VZ-52 was chambered in it, although the Indonedian Sabhara, which is a modded FNC designed for police work, chambers a confusingly named cartridge with the same length and bullet diameter, but different dimensions. While the Czech ammunition looks like a longer 7.62x39mm round, the Indonesian round is actually a necked up 223 round... VERY different. Where available, the Czech ammunition is corrosive, steel cored, and Berdan primed. This does not make for easy reloading.
This article is somewhat of a notepad for me on my eventual quest to produce new, boxer primed, reloadable 7.62x45mm projectiles. However, if someone else comes in here and provides a shortcut to the knowledge I seek, I for one certainly will not complain.
Brass is the largest hurdle. There are resizing dies, available via MidwayUSA, to take brass originally designed for one caliber and convert them to 7.62x45mm. However, these dies cost around $300 apiece.
DarinPfaff notes that he's been making and selling boxer-primed 7.62x45 Czech brass for 8 years, using the RCBS Group G 7.62x45mm 2-die reloading set. The manufacturer's part number is #56274, and (for reference) retails for $133.99 on MidwayUSA without C&R discount. Using this die set, you can reform 6.5x54 M-S, .220 Swift, or 6.5x52 Carcano brass to 7.62x45. You should trim the 6.5x54 M-S and .220 Swift brass to approximate length before resizing, and the .220 Swift brass will need the rim turned down and extractor groove deepened.
This is a picture contributed by Darin, of loaded 7.62x45mm Czech rounds, along with the VZ-52 which fires them and the RCBS reloading dies. Click the image to enlarge it.