If it's a corridor feature line you want to convert...
Make Alignment
select corridor
corridor contextual tab - launch pad panel - alignments from corridor
cmd line> Select a corridor feature line: pick the feature line to convert
Create Alignment dialog box - Name the new alignment, uncheck Create Profile (make next with more flexibility).
New Alignment will be indicated in corridor.
Make Profile of Alignment
select corridor
corridor contextual tab - launch pad panel - profile from corridor
cmd line> select a corridor feature line: select same feature line (may want to freeze the layer the new alignment is on, making it easier to pick feature line, or use the draworder command and move the alignment back).
Create Profile - Draw New dialog box - Name the Profile and set Profile Style/Label Set as desired.
New Profile should appear in the Profile of the base line alignment used in the corridor
Does that sound reasonable?