How To Run a Script in WinSCP
Try this sh "!"
OR
First of all executing commands from WinSCP can be tricky and if you are able to run few commands also,there are restrictions which you can not do fro WinSCP and should have to ultimately take help of PUTTY.
Here is the link Integrate WinSCP with Putty which will help you integrate your WinSCP to Putty,so that when you open any server through WinSCP putty will automatically connect without even asking for the password.And then you can run you command,hope that wound be of any trouble to you.
Remember you can store the connection details in WinSCP and in just one click it will connect to the server on SCP and also on Putty.
You can define your own custom command by right-clicking, selecting Custom commands and selecting Customize. Then click "Add", enter a description, e.g. Run and specifying a custom command. Try sh "!" to start with - that works ok for me, if you still get errors post your output back here. The quotes are important - only the exclamation should be quoted.