A has been said, it's something that would have evolved over time, and it would have been very culture dependent.
There were only three victories in the initial invasion I can think of: Wolcot, Twycross, and Luthien, along with the culminating victory at Tukayyid, and we know more or less what went down at each. The Jags had a sort of psudo hejira, so there would not have been bondsmen taken (though there was a missed opportunity, when the Galaxy commander who offered himself up was 'rejected' and executed; interesting to think of what a Jag Galaxy Commander could have told Hohiro and co about the Jags). We know about "Clan Victor" post Twycross. At Luthien, the Dragoons being there meant there was a lot of local knowledge about Clan customs, and we know the Dragoons at least took many bondsmen. And after spending a lot of time with the Clans, Focht knew all about Clan customs, and I think we do know that the ComGuards did take a small number of bondsmen.
After that time, I think knowledge of that custom did become more wide spread, so by the mid 50s any unit on the Clan front would have been briefed on what to do. Still, chances are any captured warriors would have been sent to HQ for the intel guys to talk with them.
I think the biggest change would have been post-Bulldog, since only after that would there have been large numbers of captured Jags to contend with. My guess is that Victor's example would have been somewhat indicative, but we also know that in many places anti-Clan sentiment ran high, so probably some units would have been more open, and some less.
As to mercs, again probably it's all about the unit. Many units, even most units, are pretty open to new recruits, and there are probably more examples in merc units than Great House units (though that's probably just because of the level of detail we get on each) but it's still possible to imagine some units being a lot less welcoming, either because of their history or because of their culture (I just can't imagine a Clanner fitting in with Wilson's Hussars, for example, weather or not they were warmly welcomed. Conversely, a very anti-Clan unit like the Crimson Crusaders might have been reluctant to take in a Jade Falcon).
This most interesting question would be tech staffs. We nearly never see them. I can imagine a merc would jump at the chance, but how often would a merc unit over run a Clan base or liberate a Clan held world? A great house unit just isn't going to be as hard up for techs, so again they'd probably send any techs off to the NAIS or comparable to help work on reverse engineering Clan tech.