1) 2 meisei with same setup (meisei version, game rom(s), bios rom, game rom filename, pal/ntsc, Z80 speed)
2) file->netplay
3) set your nickname, and connection type (Good 20fps is default)
4) both players join the same server
5) one of you creates a new game
6) other one clicks on the game at the bottom list, and joins it (it'll say "* [nickname] joined the game's partyline!" ). If it gives an error here, you either selected the wrong game from the list, or you have an incompatible meisei setup from "1)"
7) the player that created the game, starts the game
8) meisei auto resets, and says "netplay started, you are player 1" or "player 2"
9) Leave the kaillera channel window open, click on the meisei main window and play. Both players can control the msx keyboard (can be changed in meisei.ini), joystick controls joystick port 1 for player 1, joystick port 2 for player 2. Both players (and the server) will need a stable connection, or else it may time out.

Does meisei support the errors that occur when accessing (writing to) the vdp to fast?

Nah. I'd want to, but there's very little technical documentation about how the VDP operates on low level, eg. internal VRAM fetches during scanline rendering and their exact timing. Another (annoying) thing, previous tests revealed that VDP quirks aren't the same on every MSX.