Some alteration of the map may be required. Treasures should be advanced appropriate to the new CR.
1) Ledge: 4 Rat Swarms (EL 6)
3) Crumbled Courtyard: Trap Door Pit CR 2: 20' deep (2d6 damage), search 23, disable device 22.
6 Dire Rats (EL 3)
5) Secret Pocket: Search 28, disable device 27, Add giant wasp poison to the needle.
6) Old Approach: 6 Dire Rats (EL 2)
8) Pressure Plate: Search 25, disable device 24, change trap to arrow fussilade - 8 attacks +8 ranged (CR 4)
10) Honor Guard: Replace the quasit with a vrock.
12) Replace the weakened troll with a a half-white dragon troll.
14) Replace the mephit with a huge water elemental. Alternately, use a huge ice para-elemental to fit your wintery theme.
15) Meepo is a 4th level bard. (EL 3)
16) Kobold Bounders: Use the arrow fussilade trap as above. 6 2nd level kobold rogues. Remember to flank, use aid other, ect. (EL 4)
17) 8 Rat Swarms
19) 8 2nd level kobold rogues. (EL 5)
20) 6 2nd level kobold rogues. (EL 4)
21) Yusdrayl is an 8th level sorcerer. Yusdrayl's bodyguard is 6 rog2/ftr2 and equipped with tanglefoot bags. (EL 9)
23) 6 2nd level kobold rogues. (EL 4)
24) Replace with 20' deep spiked pit, Search 24, disable 23 (CR 3)
27) Scythe Trap: +12 melee (1d8+6,x4), search 28, disable device 27 (CR 3)
5 Wights (EL 5)
28) 12 Dire Rats (EL 3)
29) Replace with ungol dust vapor trap (CR 5)
30) 12 Dire Rats
Guthash adds the Multiheaded Template (4 heads, 10 HD, 125 hp) and advances size class to large. (total of +14 CON, +8 STR, etc.). (EL 7)
32) 4 goblin ftr3 (EL 4)
33) 4 goblin ftr3 (EL 4)
35) Replace with 20' deep spiked pit, Search 24, disable 23 (CR 3)
36) 6 goblin ftr2/rog1 (EL 5)
37) Advance Calcryx to very young.
40) 6 goblin ftr2/rog1, 4 hobgoblin ftr4 (EL 7)
41) 6 goblin ftr2/rog1, 4 hobgoblin ftr4, Durn is a hobgoblin ftr 7, greln is a 6th level cleric
Advance twig blight to 4HD and increase to medium size. (EL 10)
Use full strength wyvern poison on the poison needle.
42) 2 twig blight (4HD medium), 2 wights
42) Add 6 levels of ranger to Balsag. Give him as a companion a winter wolf. (EL 8)
45) Advance the Thoqqua to 9HD
47) 16 goblin war2 (EL 5)
48) Replace the bugbear with an Ogre war4.
49) 8 goblin war2, 2 4HD Thoqqua, 8 hobgoblin zombies, 2 bugbear
50) 8 shadows (EL 9)
54) 4 goblin ftr2/rog1 (EL 5)
55) 10 4HD medium twig blights, Belag is a 10th level druid, increase the gulthias tree's hitpoints to 132, Sir Braford is a fallen 6th level paladin, Sharwyn is a 6th level wizard. (EL 12)
Using the standard method of computing EL will produce numbers higher than the actual challenge presented in several of the above cases. In general, I'd add one to the EL (instead of 2) for each doubling of the number of mooks, and I'd assume the CR of a 'boss' NPC is character level minus 1 instead of character level. I've made suggestions where I think that the standard method is likely to go very wrong. If the encounter ends up harder than I think its going to be, add a point or two to the EL.
Suggested map alteration: Room #4 is 70' across. Add an additional 30' gap between the southern most row of rooms and the next row. In this gap, Room #14 is 30'x30', room #17 is 20'x30'. Also, room #41 is 50' across.
