It's far easier to use the script host because, with just a few lines of code, the script interpreter pops the service in there without you having to worry about if you added it correctly everywhere.
The setup we use in my shop is a VBScript that installs (or removes or configures) another VBScript as a service. This other script, in turn, manages when and how the binary .exe that is at the root of the service is invoked.
One nice thing about this arrangement is that by using a second script to manage the executable(which simply hosts the core functionality of the service), you can simply stop the service, tweak the script, and then restart the service, and the new changes are immediate.
We've also done the opposite, where the binary is the service that periodically calls a script that contains the primary functionality- again, the advantage is not having to recompile every time you change a parameter.
"I would rather have a free bottle in front of me, than a pre-frontal lobotomy..."
-Shrubble