..... do it 3d style then >.<
Just make a plain object lock it on position it so it's just in screen.
then you can make a box and scale it according to the loading position. For every object loaded for the level you could add 1 more to the variable, and continiously update the scale value of the object.
E.g.
Make object plain 999,800,600
Lock object on 999
Position object 999,0,0,400
`Loading bar
Make object plain 1000,200,10
Lock object on 1000
Position object 1000,0,0,400
`Loading objects and stuff
Inc Loading,2
Scale object 1000,Loading,100,100
Sync
`Load another object
Inc Loading,2
Scale object 1000,Loading,100,100
Sync
`Sync will refresh the screen, updating the loading bar...
`Remove loading screen and loading bar
delete object 999 : delete object 1000
`Main Loop
Do
`Random Code ^-^
Loop