How to use AR Transaction Type as source in SLA

I have a business requirements that dictates to have below accounting setup

a) Default account code combination source: Transaction Type

b) One segment value override

1. Specific value to be used for a specific AR Transaction Type - say ABC
2. For other transactions type, no override is requried

How can I achieve (b) above. Is AR Transaction Type is available as source in Account Rule?

(a) is no problem

Appreciate input.

Thanks,

Giri