Edi, I think you might need to start playing the game again
as I've noticed your Dom-theory seems to be more out of synch with Dom-playing-reality than it used to
Maybe your Dom-foo needs a few workouts to return it to its former sharpness
Magic movement (such as teleport/cloud trapeze) obeys similar rules to regular movement. As in all units magic move to friendly provinces, then all units magic move to enemy provinces, then all battles are resolved. Which means you can never catch a unit that is magic moving out that same turn with other magic moving units that are arriving. (which I think covers the OP's question, as the Teleport spell you get from Boots of the Planes obeys the same rules as the regular Teleport spell. All be it without the wearer needing a lab to cast the spell).
Battles from magic movement being resolved this way also means that if you magic move units to a province to reinforce a friendly army, then they will always* arrive before any enemy magic movers arrive there that have been sent to destroy the army. (such as a bunch of army killing SC's). Which is an essential gameplay mechanic, especially in the area of "setting a trap".
(*providing no factors interfere with their magic movement, such as domes, or the units being killed themselves before they could magic move. See below)
On a similar topic. You can easily tell when battles are resolved by looking at the message screen, as what you see there is the order things happened that turn. So when you are magic moving units around, you will see a bunch of messages saying "XYZ casts Teleport", and then after these messages you will see all the battle reports that occurred as a result of the magic phase. Then you will likely see another load of messages about events that happened that turn, followed by all the battle reports relating to battles that happened in the regular movement phase. (Edit - The message board can actually give you a lot more infomation than it first appears. As there is no random element to a lot of the messages, in regards the order in which they appear. As a lot of messages appear in the order they do for a reason)
And what you can learn from the message board, in relation to the magic phase, is which battles are resolved instantly upon casting, and which are resolved in the next step of the turn resolution sequence. Since there are some spells that do create *instant* battles, and can trigger before the enemy unit has magic moved, and so are caster id dependent. And no prizes for guessing that these spells are the assassination spells. Since if you cast an assassination spell like Earth Attack, you will notice that the "View Battle" option appears on the same line as the message telling you the spell has been cast. This means the result of the spell was resolved *instantly* (ie. the turn resolution stopped to resolve the consequences of the spell). So assassination spells can be used to kill magic movers before they magic move, but caster id plays a big part in it (especially if only one assassination spell is being used)
So to answer the original question in short, if you want to catch the Boots of the Planes guy, you either need to use assassination spells, and hope the RNG is kind to you in regards caster id (yet alone with the success of the spell itself). Or you need to predict where the wearer is going to appear next, and set a trap for him.
Also, I have deliberately not mentioned anything about how stealth units interact with magic movers, because I don't want to see this thread hijacked with nonsense talk about stealth armies and Pan assassins. Which is sadly always a likely prospect whenever the words stealth or assassins are mentioned on these forums