How can I define cas function of an operator(mathematical term)?

[Aleksandr94]

I have hp prime v2. I want to define operator, let's say I want to create user defined CAS operator, that computes indefinite integral: limit(int(Y,X,-A,A),-infinity,+infinity).
1) I tried to do this trough shift+ define with no success.
I was able to obtain correct integrals by using CAS.int(Y,X), but was inable to compute limits via CAS.limit(Y, X). Because it was impossible to obtain right result for limit, I was inable to obtain correct indefinite integral.
2) I tried to do this thought shift + program. I was unable to compute integral.
I used
EXPORT MYFUNC(x,y);
RETURN CAS(int(y,x));
3) I also tried to do this thought
# cas;
myfunc(x,y):=
BEGIN
int(y,x);
Result it gave was incorrect.
How can I do this?