Is it possible to get a splitter of some kind for a camcorder mic jack that allows to to record two different mono mics into two different channels?

Tony,
you can buy Y adapters at Radio Shack and most pro-audio dealers that allow you to connect 2 mono sources to the stereo/2channel input of the camcorder.
2 cautions;
1. Be aware of cable strain on the adapter or jack.
2. Be aware of potential phasing issues depending on mic placement.

How do you combat the potential phasing problems? Is it strictly mic placement?

I was looking to do something similar, with a small omni lav on a podium, and a boundary mic on a table about 15' away. My plan was to convert the stereo track to 2 mono tracks in post, and use the boundary as the main audio source, suplemented by the lav as required.

I'm fairly new to the audio world, so I don't know what phasing is, but what I did was hook a mono shotgun mic and a stereo wireless lav to one mic jack on a normal camcorder. I had to get a stereo to mono converter and a two mono to single sereo adapter and I had the shotgun mic in the left channel and the wirelss lav in the right channel. Pretty sweet!

stereo wireless lav... which make/model is this?

AKG PR81 and PT81, it's stereo alright.

It's just two channel mono on a stereo connector. It isn't true stereo, just two copies of the same mono signal.