I suggest to have the explosives as selectable weapons,
like a pistol, a rifle or an AT launcher,
only it will have a dedicated "switch to explosive" key.
If you have multiple explosives types (stachel and AP mine for example)
you would cycle them with the same button you cycle fire modes (single, auto, GL, etc)
The explosive would then be placed by clicking the primary mouse button.
Arming the explosive can be done by the scroll wheel, since it is clear that
if you have gone so far, you do actually intend to detonate it soon.
Like 3558 suggest tying the explosive to a clacker would be best
(for numerous reasons, please read 3558 why) which in turn will remove
the "TOUCH OFF BOMB" from the scroll wheel, and that would eliminate
the 2694 issue (even though it is stated as resolved).
Once an explosive has been armed only a specialist with the proper toolkit
would be able to disarm it.
An unarmed/disarmed explosive should be able to be picked up again back to the inventory.