+1 To TexLaw.
I do single decoctions fairly frequently and follow Noonan's advice. Mash-in to low 130's (for highly modified malts, which most are), wait 5 minutes, pull decoction (thickest part of mash), bring decoction to next rest temp (mid 150s), hold decoction at that temp for 10 minutes, heat decoction to boiling, boil decoction for 5 minutes, return decoction to mash... bringing mash temp to mid 150s, hold mash at that temp for 20 minutes.
Since I have a direct-fired system, I heat up the whole mash to mash-out temps. I don't think you get much maltiness from mash-out decoctions (thinner), so I don't think they're worth it unless you don't have a direct-fired mash-tun.