One possibility is this:
Mike 1 into channel 1 panned left: fader level adjusted to suit
Mike 2 into channel 2 panned right: fader level adjusted to suit
Mike 3 (your mike) into channel 3: fader level off (so that it doesn't go into the main mix)
Connect mixer to Lambda, left main output into line in 1 of lambda, right main out into line 2 of lambda. The main mix controls level going into Lambda
The above is your recording set up.
Now for your monitoring set up:
Press the 'FX to CTRL Room' button.
On Channels 1 to 3, adjust the red FX knob on each to send signal, via 'FX to CTRL Room' to the 'CTRL ROOM OUT', whose level is determined by the 'PHONES/CONTROL ROOM' knob.
Your voice is on channel 3, which is not going to the main mix because the fader is pulled down, but is going to the control room output via the FX knob. Likewise, the two using Channels 1 and 2 also go to the control room output the same way. Note also that the FX levels are independent of the faders, so you can have different level for mix and different level for monitoring.
For monitoring itself, there is a headphone socket on the mixer controlled by the PHONES/CONTROL ROOM knob. There are also Left and Right line outputs 'CTRL ROOM OUT' which can be used to go to powered speakers, or an amp, or even a headphone amp.
Thanks a lot for this. I will try setting it up this way when I get to the office tomorrow morning. I only have one mono plug for the headphones at the moment (which is then split to the two sets of headphones - hardly ideal but this is how the original soundmaster set up the studio), so I have to choose L or R, but I can just use the one most often used (the second microphone only gets used now and then) and the second person just won't be able to hear themselves I suppose. The main thing is them being able to hear me, so if I can get that working, that will be perfect. I can buy a stereo cable for future recordings. Fingers crossed!