I have a standard MIM tele, and I'm looking for less twang- a thicker tone for alternative rock kind of stuff. I've got the cash and have researched a bit, and I'd appreciate it if someone could give me some input on my pickup choices.

Neck: Seymour Duncan SH-1
Bridge: Dimarzio Virtual Hot T

Also, anyone know if Sam Ash or Guitar Center sell humbucker-ready tele pickguards and humbucker covers?

Again any input would be much appreciated.
Well you need to make sure that your teleaster is routed enough to allow a humbucker in the neck.
From what I've read all standard teles are routed stock for humbuckers
Good choice for pickups. I am more on the side of the Seymour Duncans though. I think that if you want the killer sound of a single coil at the bridge, get the Seymour Duncan STL-3. Hot, true single coil pickup. Make sure the tone pots are what you should be using for the pickups (250k on the single and 500k on the humbucker...this is only a starting point though) and then make changes from there. It is possible to get tonal and sound output to change just by changine the pots to a different resistance and changing the caps for the tone pots. Maybe change the switch to a 5 way so you can run the humbucker as a single coil and then "mate" the single from the humbucker to the single in the bridge..........or whatever you like. Just think of the possibilities...........there are a bunch. Hope this helps and good luck!!!!
Reversed pairs and staggered thirds.........all day long!