Try this structure:
No Limit Structure & Ante
Level Small Blind Big Blind Ante
1 5 10
2 10 20
3 15 30
4 20 40
5 30 60
6 50 100
7 75 150
8 100 200
9 150 300
10 150 300 25
11 200 400 50
12 300 600 75
13 400 800 100
14 600 1,200 125
15 800 1,600 150
16 1,000 2,000 200
17 1,500 3,000 300
18 2,000 4,000 400
19 3,000 6,000 600
20 4,000 8,000 800
21 6,000 12,000 1,200
22 8,000 16,000 1,600
23 10,000 20,000 2,000
24 15,000 30,000 3,000
25 20,000 40,000 4,000
26 30,000 60,000 6,000
27 40,000 80,000 8,000
28 60,000 120,000 12,000
29 80,000 160,000 15,000
30 100,000 200,000 20,000
31 150,000 300,000 30,000

Increasing every 15 or 20 minutes. You can use the same structure without the antes. Start with T1,500.
Or, if they want to use a lot of chips, use the WSOP starting structure:

LEVEL ANTE BLINDS
1ST $25-$50
2ND $50-$100
3RD $100-$200
4TH $25 $100-$200
5TH $50 $150-$300
6th $50 $200-$400
7th $50 $250-$500
8th $75 $300-$600
REMOVE $25 CHIPS
9th $100 $400-$800
10th $100 $500-$1,000
11th $200 $600-$1,200
12th $200 $800-$1,600
13th $300 $1,000-$2,000
14th $400 $1,200-$2,400
REMOVE $100 CHIPS
15th $500 $1,500-$3,000
16th $500 $2,000-$4,000
17th $500 $2,500-$5,000
REMOVE $500 CHIPS
18th $1,000 $3,000-$6,000
19th $1,000 $4,000-$8,000
20th $1,000 $5,000-$10,000
21st $2,000 $6,000-$12,000
22nd $2,000 $8,000-$16,000
23rd $3,000 $10,000-$20,000
24th $4,000 $12,000-$24,000
REMOVE $1,000 CHIPS
25th $5,000 $15,000-$30,000
26th $5,000 $20,000-$40,000
27th $5,000 $25,000-$50,000
REMOVE $5,000 CHIPS
28th $10,000 $30,000-$60,000
29th $10,000 $40,000-$80,000
30th $10,000 $50,000-$100,000
31st $20,000 $60,000-$120,000
32nd $20,000 $80,000-$160,000
33rd $30,000 $100,000-$200,000
Start with T10,000.

Edit...sorry, the tables didn't come out very well, but I think you can figure it out. On the first table, the antes, when they kick in, are the far right column. On the second table, the antes, when they kick in, are in the first column.