You can use any pump you wish to pressurize the left manifold, as the feed from the APU is out of the left manifold. Noe that the APU fuel supply is nearest to the AFT1 pump, some maintain this makes this the "best" pump to use.
In reality this depends on a lot of things, the APU suction feed can sometimes "overpower" a distant/weak boost pump, which is why some maintain to use the nearest pump. This is rare, but can occur.
