To install, follow the steps:
1) Unpack the archive into "coremio/modules/Payment"
2) Go to the admin panel, section Settings -> Billing -> Payment Gateways
3) Find the "Yoomoney" module
4) Specify gateway settings
5) Save settings
6) Activate the payment method in the "Activated" -> "Activated Payment Gateways"

After that, the module has been successfully installed and configured.