The last parameter in SetPlayerPos function sets the interior of a player. Unfortunately there are no pages at VCMP Wiki that contain interior IDs. Try making your own list, gl.
Correct, VC:MP 0.3z Doesn't use any interiors ID to be setted up, so, its get the current interior of the current pos of the player, , VC:MP 0.4 I guess it contains the interiors id and their function.
Good Luck
SetPlayerPos(playerid,Float:x,Float:y,Float:z,Float:r,inter), where
inter - The interior to position of player at.
huh?