u can do that easily on your own. there is one tuorial for 06 but it works for 07, too.
edit: i made once a bootup for 06 for myself. here you go, if you like it:
klick to enlarge
here is the file you need:
http://rapidshare.com/files/4811193/screens_bootup_title.big.html
you just have to put it in you live 07 sgsm folder.
if you like to make one on your own:
1. open the file i hosted with BigGui (its in the nlsc database)
2. export the title.fsh
3. upen title.fsh with fshX (also in nlsc database)
4. export the picture as bmp.
5. open in Photoshop (or another program to edit pictures)
and if you're done, do all the steps backwards.
1. import it with fshX in title.fsh
2. save (or just exit)
3. import the title.fsh with buggui in the screens.... (the one i uploaded)
and replace it with the existing one.
4. save (or exit)
5. place it in your sgsm folder
and youredone. its very easy.