Neoloader don't implement this feature now,But there is two parameters refer to downloading from URL in Magnet URI scheme.
Web links to the file
There are two types of download links that a Magnet link can include as a direct or backup source.
"as" ("acceptable source") refers to a direct download from a web server. Regarded as only a fall-back source in case a client is unable to locate and/or download the linked-to file in its supported P2P network(s), most clients treat it equal to the "xs" token when it comes to priority, and ignore the timeout before contacting "as" sources denoted by the specs.
as=[ a web link to the file(URL encoded) ]
"xs" ("exact source") is either an HTTP (or HTTPS, FTP, FTPS, etc.) download source for the file pointed to by the Magnet link, the address of a P2P source for the file or the address of a hub (in the case of DC++), by which a client tries to connect directly, asking for the file and/or its sources. This field is commonly used by P2P clients to store the source, and may include the file hash.
It will be perfect if Neoloader implement completed Magnet URI scheme.