You can at least get a Safariland CompI for an SP101:
http://speedloaderstore.com/contents/en-us/d45.html
I don't own an SP101, but my bet is that it has the same chamber spacing as a j-frame, in which, it's the same speedloader.
While Safariland doesn't make a 5-shot CompIII, Buffer Technologies make a 5-shot Jetloader that'll fit an SP101. You can get them from
Power Custom.
CompIIIs & Jetloaders aren't as carry-able as CompIs & IIs, but for competition and general range use, they rule. I use Jetloaders, and can recommend them if they fit your application.
You can also get SL Variant speedloaders for the SP101 from
Bob Macs. SL Variants can be tough to find, and Bob Macs runs out occasionally as well. They are push-release as well, and like the CompIII/Jetloader, are spring-activated. You can also buy an extended handle for them, so they can be used in carry (without the handle) or competition/fun (with the handle) mode.
If you like the twist-release type of speedloader, and want a little bling, check out the
5-shot speedloader from 5Star.
You can get the cylinder machined to accept moonclips.
TK Custom specializes in this, and has
moonclips for the SP101. The cylinder is machined so that you can still use (and unload) the gun without moonclips. There are a number of considerations in going this route, and given that there are several speedloader options available, it's something I'd consider only if my
primary interest is having my gun converted.