yeah, it could be, but it would have to 256-byte aligned, like Galandros said. You're looking at a 257-513 byte increase in program size. The table would be where he said or between $9A00 and $9B00, $9B00 and $9C00, or so on.
It's 257 bytes because the i register, or the interrupt vector, serves as the high byte of an address where the lower byte is essentially random. (It has some structure, documented in AsmIn28, but I can't remember it). Because the read address could be anywhere between $xx00 and $xxFF, you need another byte to complete the two bytes it reads in case it reads from $xxFF.

is there a way to control the speed at which an interrupt is executed compared to the rest of the program? Otherwise I think sound might slow the game down way too much

Mhmm Raylin you suggested this command about 4 times already. I think it is becoming clear it is not in his priorities since all you need to do is use Line() (altough I think this is larger). By now it is in his planned features I am certain

I think this will be for the back-buffer.

For inverted rectangles, do you mean white outline with filled black?

I think that could be possible to do through a routine like I posted in the other thread, but I would need to think about a way to make sure it's fast enough

Woot. Many thanks, Builderboy.

Alright here is a super fast filled inverting recangle thingy.  It does use a fair number or variables though, if thats a problem you can always use memory locations instead.  So here is the code (its rather long)

Lbl RC
A^8->O
255->M
While O
M/2->M
O-1->O
End
C^8->O
255->N
While O
N/2->N
O-1->O
End
A/2/2/2->A
C/2/2/2->C
For(F,B,D-1
F*12+L6->J
{J+A} xor M->{J+A}
{J+C} xor N->{J+C}
For(G,A+1,C
{J+G} xor 255->{J+G}
End
End
Return

Its very fast, but if you want something smaller, you can use this:

Lbl RC
For(F,A,C-1
For(G,B,D-1
Pxl-Change(F,G
End
End
Return
For both, the input is A,B for top left corner and C,D for bottom right corner.