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The count-in can be panned but you likely will not happy with what you need to do to achieve the results you desire.
Depending on the drums selected by the style the count-in maybe midi or audio. Midi count-in audio isn't generated by a soft synth but instead is generated by the default media player in Windows. Some RealDrums audio files include both the count-in and the drum playing audio. Whichever way the count-in sound is generated would likely change every time a different style is selected.
Because the count-in is handled dependent on style selection the best option might be to render the drums to an audio file, bring the rendered audio file into a daw, automate the panning as desired, save the panned audio file then import the audio file back into Band-in-a-Box. Then you can disable the count-in and mute the drum track.
To change the count-in settings, press Ctrl + E to open Preferences and press the Count-in/Met button
2019 BiaB (627) UltraPlusPak RB 2019 (Build 3)
Cakewalk by Bandlab - Audacity - Zoom MRS-8 recorder
i3 laptop, 64bit Win 7, 8 GB ram, 480GB SSD
Music at: http://fogle622.wix.com/fogle622-audio-home