It's a good idea although I haven't done any experimenting with mount gear. Looking at your research I'd be willing to bet swap_equip is a command to swap two rings/bracelets/etc that are both worn, rather than swapping between gear slot and inventory. If you equipvdl without unequipping first, the worn piece goes to that inventory slot, effectively swapping the pieces.
That's all the input I have unless you think the command variables might be database entries rather than names -- you can look up IDs using the DarqUI utility, as in:
Or in EQ2U
, same thing.