We tried stuffing around for ages and was sure it wasn't correct and then this obvious method by a simple cable "seems" to do the trick ,
although some 'genie-arse' could let us know about sync/latency , etc,
it gets all rather confusing on the live preferences, but i'm quite happy so far with having Logic instruments in Live
We haves an < optical/toslink/digital > cable from the mac built-in-digital output connected to our soundcard (MOTU Traveler)
so the midi-audio setup is like this

the Logic preference like so

the Live preferences comme ça

you can see reason rewire in live and combining a lead from Logic and a bass from Pro 53

We likes too much reason combinator drum machines,( which rip shit btw)
So Reason drum Machines, Logic synths (whatever), running thru Live where it can all be re-sampled . . . mmm, looking forward to this "awesome threesome" , anyone else tried it like so ?
So please tell us exactly how to do this without cable, (yes we feel dumb, only apprentice sound-persons we are) can't seem to folllow 'Gomi's' tip to the letter...
or does the cable method does just as good ?
Can we see some picture(s) of your preference(s), pleez