Sounds like you got the right idea. You could use the AUX / Booth out on the mixer for "live mix" and one channel of headphone jack for cuing.
I hope you are good with a soldering iron!!! Radio Shack and some heat-shrink tubing might just do the trick.

When I investigated in-ear monitors a while back, I read a post from Laidback Luke on his forum about how his Dad made him a little box which sounds just like what you want.

It's a feed from the cue and booth signals, which he controls with a couple of knobs. Shouldn't be terribly hard to make.

I don't have a link but I found it just searching around so I'm sure you could too.

I'm useless with soldering iron,I suppose a mini mixer might do the trick,headphones to one channel,aux out to another channel,pan one hard left the other hard right,then plug heaphones into mini mixer?

One of these mixers
www.behringer.com

this cable from headphone output to channel 1, panned left
www.thatcable.com(1-4inch)-Stereo-Jack-Plug-to-2-x-Mono-Plugs-Cable

this cable from booth/rec out to channel 2, panned right
www.musiciansfriend.com

channel 1 > channel 2/3 on the mixer
and channel 2 > channel 4/5

link fail... triple post fail

@dj disgrace thanks that looks just the job,do you use one yourself?

I have used it, yes. Works great for late night mixes in the apartment, or at clubs with no monitor (or space to bring my own). I have the 802 mixer, gives me a bit more flexibility for other uses and eq control on the channels, but the 502 would still get it done.

That's one of the features that I miss (split cue). My Behringer mixer had it, but the TTM57 does not.

Bigg Bear - What plugs do you have on your Aux/Booth output? 1/4 - RCA - XLR?

@dj reflex I come across this problem occasionally and its when I turn up somewhere and the installed mixer has not got split cue.
So if I can come up with a good solution will just put it in my dj bag and use it as and when.
Personally I would not want to buy a mixer without split cue,having said that I'm interested in the new pioneer xrdj or whatever its called and this looks like it has no split cue but for what you get,for home use or small gigs might just bite the bullet and come up with a workround for split cue.
Never seen a rane mixer over here in the uk,but hear that they sound very nice,I can't understand though why a main mixer manufacturer would not put split cue on a high end mixer,I'm sure its not difficult to do!
Maybe and I'm guessing here if the rane mixers are more aimed at the scratch dj market then they figure that blending or long running mixes are not what the end user is intending to do.but like many times before I could be wrong.

Just another thing on split cue I've been using it that long that its almost like I've rewired my hearing.In a social situation in a bar or restaurant or somewhere with lots of noise its almost distracting cause you can have someone talking to you and you're listening with one ear but also hearing other conversations with the other and your kinda like listening to 2 things at the same time,but your hearing is trying to process both!

i've favoured split cue headphone mixing for over 7 years now... as a result my hearing has improved and my h'phones volume is much lower when out gigging... on tour two years ago with Calvin Harris his rider specified approx. 144db of stage monitors yet he wore Sennheiser HD25's and bespoke inner-ear earplugs... couldn't figure that one out!