You mean can you "set" a value to it and have that be the value without doing a regular set action?
About the only ways to programmatically insert values without going through the normal set action of a data source are
The scripting data source if 'Saves historic' is checked. Then all set() calls will bypass logging type, the data source, and events (detectors, meta points, etc.)
The data file data source if the new values are older than the existing values.
Other things, like the point data import, will also bypass the data source in creating a value history.
The HTTP parameter name is the incoming format. The GET request from the publisher will look like http://yourip/httpds?parameterName=value@time&otherParameterName=value@time
The Set Point Name is the outgoing format, as I described,
setPointUrl?name=setPointName&value=value@time