Could someone please point me in the right direction regarding these, if there's something consolidated on them? I've found stuff on using 2 diseases, but nothing on the single disease Howling blast stuff, and I'm a little lost on where DnD fits in, and if the spec is any different from the cookie cutter one really, and if the single target is much different, etc...
So yeah, any sort of direction or just post here would be greatly appreciated. Thanks.
DnD is not that great for frost, maybe as a decent opener against large packs, but really not worth using at all against single target.
Some people use the Glyph of HB to do a single disease rotation, the spec is basically the same as double disease, but your rotation changes a bit. The single disease rotation is pretty simple, the idea is to use HB as often as possible (single disease OB can actually be less powerful than a single disease HB). The basic idea is HB->OB->BS->BS->(FS Dump)->HB->OB->OB. If you have Blood Tap available you can use it for a third BS, or some people use BT to push in the second disease ditching one BS, using something like HB->PS->(BT)OB->BS->(FS Dump)->HB->OB->OB, but I personally don't like the feel of this second variation. Never IT.
The rest is basically the same as double target rotation. Use your KM and Rime procs smartly. Deatchill on HB or FS as long as KM is not up.
Edit: for glyphs, I like HB (of course) + FS + RS (I'm currently testing the glyph of OB in the place of RS, and it's not as bad as I had imagined, so it's viable as well).
Disclaimer: I don't claim this rotation is better threat-wise than a double disease rotation, I like it because it still provides enough threat (and very close to double-disease) but the rotation seems smoother to me (no IT, PS, Pestilence, etc.). It's really a matter of personal preferences rather than mini-maxing for me.
I don't use HB for single targets unless I get in trouble with threat for some reason, but that shouldn't happen if you're exp capped and you're hitting your target. For single targets I'm able to basically ignore the threat meter and go for DPS.
My glyphs are HB, OB, and UA though you could definitely switch UA with FS.
My single-target rotation usually goes something like IT, PS, OB, BS, rune dump in FS, depending KM and Rime procs. Get an add-on that you can use to alert you to those procs and use FS, OB, and HB effectively and you'll be a threat-generating, tank DPSing machine.
The glyphs for Frost are simple, Oblit, IT and either RS or HB. FS is not a real good choice, in my opinion, for frost tank in that with the current amount of avoidance available RS will be your highest threat attack in that it will be used as often as possible. Rotation, just like Blackshirt said, you wanna use IT-PS-OB. A lot of frost tanks don't use OB 3rd due to they want deathrunes available first. The amount of proc's that Frost has negates that effect. You will have something proc in nearly every other rotation. Single target threat in frost is sometimes greater than blood when Ryme and Killing Machine proc sequentially. Good luck out there.