The short answer?
No and no.
The slightly more complex answer?
Yes and yes. Unfortunately this would require heavy work on the kernel to replace the boot screen, AFAIK. On the password screen, it'd take some re-coding in the Qtopia source code. Unfortunatly, Sharp uses modified code from the GPL Qtopia, and I don't even think 1.5.0 Qtopia is available for download anymore.
But the sort answer is probably the most relevant. Hard to do.