Since I've tapped out the Highlander franchise, why not look at another film from the 90's?
The Wild, Wild West ran from 1965 to 1969. Creator Michael Garrison envisioned it as James Bond on horseback. When the movie came out, changes were made. My take would be a bit different.
1869-the Civil War is over, but the feelings still linger. US Army Captain James West is busy hunting down outlaws, most notably Confederate General McGrath. Rumors that McGrath is building another army. Sneaking into McGrath's hideout, West stumbles into US Marshall Artemus Gordon, who's looking for some scientists that he believes that McGrath kidnapped.
A shoot out occurs and McGrath escapes. West is telegrammed to come to DC, where he meets President Grant (Robert Conrad). It seems that McGrath is working under orders, but they aren't sure whose. West is partnered with Gordon to figure out who's been kidnapping scientists. Gordon has a clue though- McGrath's invitation to a masked ball to be held in South Carolina. With forged credentials the pair slip into the party. Things are odd though, as while there are plenty of Confederates there are also representatives from England, France, and Spain. Way too many movers and shakers for a simple plan of revenge. Who is behind this?
It turns out that McGrath is little more than a pawn. The king in this case is Dr. Miguelito Quixote Loveless (Peter Dinklage). Dr. Loveless promises to provide all in attendance with their deepest desire. Namely he'll give the USA over to them with the weapons he'll be auctioning off to the highest bidder. While the Civil War may have been a bloodbath, Dr. Loveless found it inspiring. The ideas that came to him showed him new ways and weapons to wage war. Weapons capable of flight, of going through a line of troops like a sword through butter, and chemicals that they've never heard of. The auction will take place at Loveless's private estate in one week's time.
Also if anyone can happen to murder the two US agents on their way out, that would be delightful. West and Gordon are in trouble, but one of the dancers saves them with a well thrown stick of dynamite. Rita Escober (Selma Hayek) introduces herself. Namely she's an agent for the Mexican government. The word of Loveless's plot has reached them, and Mexico is rather keen not to be under Spain's rule again, so the three by train head west towards the auction.
The three slip in and discover Loveless's weapons, namely airplanes, tanks, and steampunk inspired weapons of death. Rita and Gordon steal one of the planes and strafe the compound while West slips inside and fights through the various deathtraps inside to have a showdown with Dr. Loveless. The good guys win, the weapons are destroyed, and they ride off into the sunset. Dr. Loveless leaves a small music box on the train. Not a weapon, no, just a small token of appreciation to a well played game. He'll try harder next time though.
As far as a casting goes, I'd more or less leave it alone. Although if I had my druthers I'd have Bruce Campbell instead of Will Smith. Smith is a fine actor, but then again I'd put Campbell in pretty much every film.