How do I generate one single form? (As opposed to using adadmin to generate them all)

Character mode forms: Use adfrmgen
Usage : adfrmgen filelist=
or : adfrmgen product="product shortname(s)" [filepath="dir-path/filename"]
For example :
adfrmgen filelist=filelist.txt
adfrmgen product="gl" filepath="forms/GLXSSMTY.inp" (one file)
adfrmgen product="gl" filepath="forms" (entire directory)
adfrmgen product="gl" (entire product)
adfrmgen product="fnd gl" (multiple products)
adfrmgen product="fnd gl" filepath="forms" (entire directories from multiple products)

GUI forms: use f45gen
Usage : f45gen module= userid=
output_file= module_type=form batch=yes compile_all=special

Example:
f45gen module=/u16/appl/nca/au/1.0/forms/US/FNDCPMCP.fmb userid=APPS_APPDEMO/APPS
output_file=/u16/appl/nca/fnd/7.5/forms/US/FNDCPMCP.fmx
module_type=form batch=yes compile_all=special

Note that in Release 11, adadmin will allow you to compile specific forms