You will need to use the Private Use Area for some of the composites as not all are defined in Unicode. That also means using special keyboards for typing them. See the FAQ: How do I type Unicode characters? in the Support Forum for some methods of inputting Uncode characters.
Creating composites is easy
- First create your base glyphs and accents
- Insert characters and select from the Latin Extended sets. That will add the correct mappings for those glyphs
- Complete composites
- Adjust accents for vertical position on lowercase
- Adjust composites for position of accents on uppercase
To add those composites not defined in Unicode:
- Select the base glyph and accent in the glyph overview with control click
- Copy
- Open a new empty glyph
- Paste to create the composite
- Adjust the accent
- Map the glyph to the Private Use Area