It depends on why your lecture file is considered "ineligible". Is it too large? Is the bitrate less than 96 kbps?
One thing that you might want to try is to change the media kind so the file uses some other mechanism to sync with your iPhone - but one warning - I haven't tried this myself so I'm not absolutely certain it will work.
Select the file in iTunes, then right-click and choose "get info" (or hit "command-i" on your keyboard). Click the "options" tab, and set the "Media Kind" to something like "podcast" or "audio book" - anything that uses something other than iTunes Match to sync. The file will "disappear" out of your music listing, and move to the appropriate section of iTunes.
With luck, the next time you sync your phone you'll find the lecture in your Podcast app, or in the audiobook section of the music app, or in iTunes U, etc - depending on what you chose.
Apart from that, you can try to identify why it's not eligible, and fix that issue. If it's too large, you can try editing the file to split it into two smaller pieces. If the bitrate is too low, you can "upsample" it.
The original file was mp3 and has a bit rate of 24 kbps. I converted it to ACC 128 kbps mono. It still was ineligible for Music Match and hence, was not synced to my iPhone.
I solved my problem of getting recorded lectures, which were in mp3 format onto my iPhone by following your suggestion about changing the media kind from music to Podcast. When I did this and clicked okay, the files instantly disappeared from the Music list in iTunes and appeared in the Podcasts list. Thanks for the tip, Joseph.