Basically you should be able to do this on any preset that hilights moves, but you could use Mighty Lion Chess. Select Move or Play. Click e2 (highlights on e3 and e4 come on). Click e5. You get a popup that complains this is not highlighted as legal, and asks if you want to play it Anyway. Click OK. The problem now is that it doesn't submit the requested "P e2-e5; it submits "P e2-".
Now it is a perfectly valid stance that you don't ever want to send "P e2-e5", because the highlghts give a strong indication that it will be illegal (and in this case it certainly is). But why the popup, then? Sending "P e2-" is not what the wanted to play, and is most certainly illegal. Better just ignore clicks on non-highlighted squares completely, in that case.
Basically you should be able to do this on any preset that hilights moves, but you could use Mighty Lion Chess. Select Move or Play. Click e2 (highlights on e3 and e4 come on). Click e5. You get a popup that complains this is not highlighted as legal, and asks if you want to play it Anyway. Click OK. The problem now is that it doesn't submit the requested "P e2-e5; it submits "P e2-".
Now it is a perfectly valid stance that you don't ever want to send "P e2-e5", because the highlghts give a strong indication that it will be illegal (and in this case it certainly is). But why the popup, then? Sending "P e2-" is not what the wanted to play, and is most certainly illegal. Better just ignore clicks on non-highlighted squares completely, in that case.