Ok, sorry I've not gotten to this sooner. I played around with some 260s tonight and think I have something you can use. I only made a portion of the flag, and had no means of photgraphy - but here goes.
You'll need Black and White 260's.. You can use 160s for a smaller flag.
Begin by fully inflating a black 260. Release some air to soften it up a bit.
I shaped mine into an
S-ish shape by squeezing bends similar to how you fashion a 260 heart.
make an ear twist about 2/3 down the balloon - this will make the balloon look like an
L
Repeat this process with a second black 260.
Twist the balloons together - the 2
"L" 260s will make a rectangle shape. Bend them into a waving flag shape (S shape)
Now we start attaching balloons to the frame.
Partially inflate your remaining black 260s to the length of the height of your rectangle flag frame. Twist them into the frame vertically every 1.5 to 2" apart.
Inflate your white 260's to the lenght of your flag frame. Twist them into your flag frame and weave them in between your vertical black 260s, and finally lock them by twisting the other end into the flag frame.
Sorry for the crappy imagery - but it's all I had access to tonight. If you can make any sense of it, goodluck. I'll try to put one of these together this weekend at my theater gig and get some photos up :/