Hi André,
Thank you for the link for reference! I have the multi-select working. But my requirement is a bit different.
Maybe I will tweak the requirement a bit to make it more understandable (I wish I could post a screenshot)
TextBox1 = Take values separated by commas or semi-colons from the user,
TextBox2 (multi-select capable lookup) = based on the values given in the TextBox1 control, mark records in the lookup.
Regards,
Abhinay