If you're only doing ANSI X12, the ISA segment should be easy for you to parse, as it is a fixed length.
Position 4 will give you the element delimiter (field delimiter).
Position 106 will give you the record terminator.
Position 105 will give you the subelement delimiter
You probably won't have much use for the subelement delimiter, depending on the document type.
Once you figure out what your field delimiters are and then the record delimiter, it should be a snap.
(Standard disclaimer: there are many great tools out there in the form of data translators that make this job much simpler than having a programmer reinvent the wheel. Some of these tools are even open source and free. Just sayin'...)
Hope this helps.