Just an idea, but maybe you could use a mouse via OTG in the meantime.
You could use Tasker (Paid) or Llama (free) and create a profile to disable the screen timeout while charging.
When using Llama just remember to create another profile to enable the timeout again, when diconnected....
This post by dr.ketan makes it really easy. No need to install anything on your PC or use the command line.
In his post scroll down to the 16Nov11 Simplified part and follow his instruction. Takes 10 minutes at most and half of it consists of wait...