As a frost deathknight.. Rogues should not be hard at all.
I even killed one when I was not wearing a helmet, chest piece, and shoulder piece. Ok, so here is the guide.
A good rogue will usually stealth before attacking you, and if he dosen't you wont even need this guide. If he does, then follow the guide.
After he stealths, call out your ghoul (Need glyph or corpse dust if there are no body's around.) then use your death and decay where you are standing.
The rogue will attack you, and most likely stun you.
While you are stunned your death and decay and ghoul will be damaging him.
When you are no longer stunned, Use your chains of ice on him so he cannot run.
Then cast icebound fortitude. After you do that, use this macro for the whole battle:
#showtooltip
/castsequence reset=dead/target Icy Touch, Plague Strike, obliterate, blood strike, blood strike, frost strike
If you really need to heal, use deathpact on your ghoul, and if you are getting low on hp, use deathstrike.
This is not much of a guide, but you will beat a rogue if you follow it.[/COLOR]