The short answer is… no.
The longer answer is, as BobT suggests, wait a few months/years and someone will probably air them somewhere else.
It’s not as bad as it sounds, though. In the glory days of the Big Three Networks (i.e., pre-cable) you might never see those unaired episodes again, ever. However, with today’s proliferation of cable networks desperate for content, I guarantee that every minute of professionally produced footage will eventually see the light of day. Just look at TVLand. Besides their regular schedule of popular, long-running series, on weekends they’ll often air episodes of series that lasted such a short time, no one ever bothered to try to syndicate them (no chance for profit). Hell, I’m an avid TV watcher (it’s my business - seriously!) and they consistantly pull out shows I’ve never heard of. That’s tough to do!
And as far as going directly to the network (or more likely, the production company - the networks don’t necessarily the programs they air) - ain’t no way in hell! Maybe if you knew someone on the production staff who had his own copy, etc…
The networks/large production companies just aren’t going to open their vaults to shmucks like you and me.