Hello from Spain!
I'm also a big fan of Steve Farris, Steve Lukather and Steve Stevens' sounds and after many years of seaching I've reached to have their same (?) sound or really very very close. I now own an Axe II XL.
Mr. Mister's Broken Wings lead sound was made with a Dumble amplifier, with a Boss HM-2 ( heavy metal) pedal and with a Boss CE-1 chorus. For the speakers, as far as I know, he used many 1x15 Electro Voice, but I use the 4x12 Cali or the Celestion Vintage 30, the get a very close sound as the original song. He used also Keeley amplifiers, but for the clean sound, I guess. He used also the vintage Ibanez rack delays. His guitar was a beautiful orange Charvel with Fender strat style headstock.
Steve Lukather use and has used many different amplifiers and rack gear during the 80's and 90's. On the first 80's he used Marshall Plexis. But on the Seventh One album released on 1987, he used a Mesa Boogie Mark IIC+ with Mesa cabinets and speakers. His secret weapon (the same as used by Michael Landau and Dan Huff) was the Dytronics CS-5 Tri Stereo Chorus (also released with the Dyno My Piano and Song Bird 1380 brands). You can find the same sound on the XL as Triangle Chorus on chorus block. I have the Fulltone TERC reedition and I can assure you the Axe sound equal or even better than this unit, and it's an exact remake of the Dyno My Piano, accordin to Mike Fuller. He used also Dbx 160 compressor, Roland sde-3000 delays and Lexicon vintage 80's reverbs.
On 1990 he changed is amp gear to Soldano, using the amazing X88R preamp which was designed by Bob Bradshaw, who was Lukather's tech on TOTO tour during almost five years. The preamp was build by Mike Soldano, but was Bradshaw idea. The amp he used was a VHT, one of the best rack amps in the world.
After this, Bow Bradshaw released his state-of-the art CAE 3+ preamp and Lukather changed to this amazing piece of gear. As far as I know, now he is using Bogner amplifiers.On Tambú álbum he used Rivera amplification, and he was working close with Paul Rivera and designed the Los Lobotomis guitar cabinets with more headroom and bass than normal 4x12 ones.
And for Steve Stevens I can tell you that on those years he used Marshall 800 modded by amps gurú Marty Friedman for lead sounds, and Rockmans for the clean sounds. Nowadays he has a Friedman signature model
Greetings from Spain!
But isn't it a coincidence?? So many great steves in the guitar business, steve lukather, steve morse, steve lynch, steve vai, steve stevens, steve miller etc. the list is really endless 
