Matrices can only be textured with textures all stuck in one image. The trick, if you want them seperate is to load them individually, paste 'em on the screen, then use 'get image' to bung 'em all into one image.
PS There is no need for all that bitmap stuff you are doing. You can simply use LOAD IMAGE to load graphic straight into an image number (can be bmp,jpg,png...)
If you are unsure of any of my code, then just ask.
sync on : sync rate 0 : autocam off
imageres=128
load image "sq1.bmp",1,1
paste image 1,0,0
load image "sq2.bmp",1,1
paste image 1,imageres,0
get image 1,0,0,imageres*2,imageres,1
make matrix 1,1000,1000,8,8
prepare matrix texture 1,1,2,1
t=1
for f=0 to 7
t=3-t
for g=0 to 7
t=3-t
set matrix tile 1,f,g,t
next g
next f
update matrix 1
position camera 500,800,100
pitch camera down 70
do
sync
loop
Boo!