I wish I could help, but I spent volumes of time with the MCP2140A (it had the voltage range that I needed), but I never got it to work. I looked for help on the forums here, at Microchip, and from the Microchip tech support, but not many people use these chips, so there wasn't a lot of help to be found.
The only thing I can suggest is to try to copy the design from the demo boards - I copied the design for the board with the MCP2140 (old version of the MCP2140A), and you might have more luck since there are demo boards that use the MCP2155. Also, you should be able to check the J2ME app with a PC that has an IrDA port (or if you get a USB-IrDA adapter). If you get the IrCOMM2k virtual com port driver, you could send and receive data it from hyperterminal on the PC.
Right now I'm trying to implement the IrDA protocol with the MSP430 MCUs, although I considered using the PIC24s. Both support IrDA without an additional chip between the MCU and the IrDA transceiver, and you can debug them since the stack is implemented in code. The PIC24 stack is a bit larger (if I remember correctly) - I think they implemented the full stack, so it might not fit on all PIC24 chips. The TI stack is IrDA lite, and written in assembly (close to 1000 lines of assembly, so no cakewalk...).
Wish I could be of more help - good luck!