This program example will cut a 100mm dia hole 50mm deep at XY zero: -
0 BEGIN PGM 1 MM
1 TOOL CALL 1 Z S1000
3 LBL 1
3 CC X0 Y0 ; DEFINES ORIGIN OF POLAR CO-ORDINATES
4 L X0 Y0 R0 F5000 M3
5 L Z0 M8
6 LP PA0 PR50 RL F500 ; MOVES TO START POINT WITH CUTTER COMP
7 CP IPA5400 Z-50 DR+ ; COMPLETES 15 REVOLUTIONS. THIS IS THE MAXIMUM ANGULAR MOVEMENT THE CONTROL WILL TAKE ON ONE LINE.
8 CP IPA360 DR+ ; BOTTOM PASS - MAY OR MAY NOT BE REQUIRED
9 L X0 Y0 R0
10 L Z0
11 LBL 0
12 STOP M30
13 END PGM 1 MM
Notation may not be perfect as its from memory. Obviously values are replaced with Qs if you are making a parametric cycle, and you will need to use some logic functions to work out total angular movement if you require a specific pitch or if you want to specify direction, bottom pass, internal/external options.
Let us know if you need further clarification (ie if you haven't worked with polar co-ordinates before).