Custom Instruments?

Dorico
5

You can do this by hacking an XML file. There is a tag that can be added after the clef definition.

Examples:

For an instrument in D

<clef number="1">
	<sign>G</sign>
	<line>2</line>
</clef>
<transpose>
	<diatonic>1</diatonic>
	<chromatic>2</chromatic>
</transpose>

For an instrument in B♭

<clef number="1">
	<sign>G</sign>
	<line>2</line>
</clef>
<transpose>
	<diatonic>-1</diatonic>
	<chromatic>-2</chromatic>
</transpose>