I think I know what causes the problem where if you're not a male/female and you're not one of the three normal starting classes you won't be able to complete the endar spire->taris cutscene successfully.
In the module STUNT_00 there is a cut00_convers.dlg. Each of the starting entries for this file has a startingconditionals script associated with them. The scripts that fire are:
k_small.ncs for male scoundrel
k_small_female.ncs for female scout
k_medium.ncs for male scout
k_medium_female.ncs for female soldier
k_tall.ncs for male soldier
k_tiny.ncs for female scoundrel
If you're not one of the above combination, then the conversation will proceed no longer (and you're stuck in the cutscene). This conversation eventually calls k_ren_visionland which loads tarm02af module.
One fix for this is to add a starting entrylist to this dlg file which has no script associated with it (blank "active" field). This way, you can get pass the cutscene regardless of your combination.
Now, if you do this, you'll run into another similar problem. In the module tarm02af (Taris apartment) there is a tar02_carth022.dlg file that also contain class/gender check. This is found in the third ReplyList's EntriesList field. The associated scripts this time are:
k_pend_bedtall.ncs for male soldier
k_pend_bedmed.ncs for male scout or female soldier
k_pend_bedsml.ncs for male scoundrel or female scout
k_pend_bedtiny.ncs for female scoundrel
Again, if you edit this .dlg file and add another entry with no script in the active field, you would be able to get pass this dialog.
I stopped testing at this point, but there may be other cutscenes dialog file that you need to edit if you want to play through with a nonstandard class/gender combination.